International Boundary Study
No. 49 – May 15, 1965
Bulgaria - Turkey
Boundary
(Country Codes: BU-TU)
The Geographer
Office of the Geographer
Bureau of Intelligence and Research
INTERNATIONAL BOUNDARY STUDY
No. 49
BULGARIA - TURKEY BOUNDARY
TABLE OF CONTENTS
Page
I. Boundary Brief............................................................. 2
II. Background.................................................................. 2
A. Political Geography.................................................. 2
1. Early History......................................................... 2
2. Ottoman Period................................................... 3
3. The Balkan Wars................................................. 3
4. World War I.......................................................... 4
B. Physiographic .......................................................... 5
C. Ethnography.............................................................. 6
III. Analysis of Boundary Alignment ............................ 8
IV. Treaties and Other Acts ............................................. 10
V. Summary ....................................................................... 11
The Geographer
Office of Research in Economics and Science
Bureau of Intelligence and Research
BULGARIA - TURKEY BOUNDARY
I. BOUNDARY BRIEF
The Bulgaria - Turkey Boundary is 149 miles (239.5 kms.) in length and is demarcated.1
Beginning at the mouth of the Rezovska (Rezvaya) River on the Black Sea, the
boundary follows the river a distance of 41 miles (66 kms.) to the confluence of the
Pirogu and Deledzhi (Deliva) Rivers. The boundary then follows the course of the Deliva
in a generally northwesterly direction a distance of 9.5 miles (15.25 kms.) where it
leaves the river. The line continues in a northwesterly direction along ridges
demarcated by boundary pillars a distance of 10.8 miles (15.75 kms.) to the Golema
(Veleka) stream. The Golema forms the boundary for 1.2 miles which then follows land
markers in a generally southwesterly direction a distance of about 59.3 miles (95.5
kms.) to the Tunca (Tundzha) River. Continuing southward in the Tunca for 7.5 miles
(12 kms.), the boundary leaves the Tunca at boundary marker 280 following
southwestward, then westward on land for 11.6 miles (18.75 kms.) to a tributary of the
Kalamitsa River, thence continues on the Kalamitsa a distance of 5.4 miles (8.75 kms.),
and follows a final straight line segment of 3.4 miles (5.5 kms.) southeastward to the
Greek tripoint on the Maritsa River.
The boundary and location of the pillars are shown on sheets 1 through 14 of La
Commission de Delimitation de la Frontiere Greco - Bulgare (Turkiye - Bulgaristan
Hududu) drawn by the official boundary demarcation commission of 1921.
II. BACKGROUND
A. Political Geography
The Bulgaria - Turkey Boundary like that between Turkey and Greece2 centers on
control of the key landbridge connecting Europe and Asia known as the Straits. The
boundary region's strategic importance recognized and fought over since ancient times
has not only involved interests of all countries in the vicinity but also the rival interests of
the Great Powers.
1. Early History
In the first century A.D. the boundary area was a part of the Roman Empire which
controlled the entire Balkan Peninsula. During nearly three centuries of Roman rule the
area prospered, until progressively increasing numbers of "barbarians" assaulted the
frontier outposts of the Empire.
The defeat of the "barbarians" in the historic battle of Adrianople (Edirne) in 378 A.D. on
the Maritsa was a major victory in Rome's struggle to maintain the empire's frontier on
1
Measured in the Office of the Geographer on the official 1:25,000 maps of the Boundary Commission.
2
See International Boundary Study No. 41, Greece - Turkey Boundary, November 23, 1964.
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the Danube River. Nevertheless, the entire Balkan region soon was occupied by Gothic
and other Teutonic tribes. Great Slavic invasions commenced in the sixth century.
Crossing the Danube, they later occupied the entire Balkans in such numbers as to give
a Slavic character to the Peninsula.
The Asiatic Bulgars believed to have arrived in the area about the same time as the
Slavs gradually merged with the Slavic peoples. By 670 A.D). the Bulgars established
themselves south of the Danube around Varna. While conquering, the Bulgars were
absorbed by the more numerous Slavs, adopting the culture and language while
retaining their own name and political organization.
Until the Turkish conquests of the Balkans in the fourteenth century, the fate of Bulgaria
varied according to the relative strengths and weaknesses of its rulers, and that of the
Byzantine Empire headquartered at Constantinople.
2. Ottoman Period
The Ottoman Turks crossed the Dardanelles about the middle of the fourteenth century
to commence an energetic campaign against the declining Byzantine Empire.
Adrianople, a key city on the land bridge, captured in 1361, became the Ottoman
capital; Plovdiv (Philippopolis) was taken in 1364, and Sofia in 1384. In 1389, the Turks
defeated the Serbs, their Rumanian allies, as well as the Bulgarians. Constantinople
itself withstood Turkish onslaughts until 1453.
Bulgaria remained under Turkish domination until the Russo - Turkish Wars of 1877 - 78
when Russian forces advanced to Chatalja near the Bosporus. She then became an
autonomous tributary of the Turkish Sultan. While the Powers at the Congress of Berlin
in 1878 limited the expansive proportions that Russia desired ceded to Bulgaria in the
Treaty of San Stefano (March 3, 1878), the Treaty of Berlin (July 13, 1878) established
a compact State of Bulgaria extending from the Balkan Mountains to the Danube River.
Bulgaria's subject status under the Ottoman Sultan remained.
Political and territorial change quickened in the years preceding World War 1. Within
Turkey, there was increasing demand for governmental reform and elimination of
cumbersome Ottoman administrative machinery. In the Balkan provinces, growing
forces of nationalism and independence, accelerated by increasing rivalries among the
European Powers seeking to eliminate the "sick man" from Europe, all converged
toward political collision. In 1908, Bulgarian Prince Ferdinand, taking advantage of the
Young Turk revolution which rendered the Turkish Porte temporarily powerless,
proclaimed himself Czar of independent Bulgaria.
3. The Balkan Wars
Bulgaria's independence whetted and magnified memories of the Bulgarian Empire in
medieval times. A secret treaty with Serbia, followed by similar agreements with
Greece and Montenegro committed the Balkan Allies to drive Turkey out of the Balkans.
Arrangements were made while Turkey was at war with Italy (1911 - 1912) which ended
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with Turkey enfeebled. In October 1912, the First Balkan War began, shortly thereafter
the Bulgarian Army took Mustapha Pasha (Svlingrad) and Kirk Kilisse (Kirklareli), and in
March 1913 captured Adrianople itself. The Turkish Army retreated to within twenty-five
miles of Constantinople to the Chatalja defense line, thus reducing European Turkey to
the Chatalja and Gallipoli peninsulas.
However, the success of the Balkan League countries exposed their separate
ambitions. In the ensuing Treaty of London (May 30, 1913) between Bulgaria, Greece,
Montenegro, Serbia, on the one part, and Turkey on the other, all territory west of a line
drawn from Enos (Enez) on the Aegean to Midia (Midye) on the Black Sea was
relinquished by Turkey.
The fighting against Turkey ended; the Balkan Allies turned against each other.
Bulgaria's claims included in the earlier secret agreements were frustrated by Serbia
and Greece. As a result Bulgaria attacked the Serbian and Greek Armies along the
Macedonian frontier in June. Thereupon began the short but intense Second Balkan
War, in which Turkey and Rumania joined Greece, Serbia, and Montenegro, against
Bulgaria. With Bulgaria fighting on nearly all flanks, Turkey recaptured Adrianople
easily. An armistice took place in July and a Treaty of Peace was signed at Bucharest
on August 10, 1913 between Bulgaria and her former Allies. A separate treaty with
Turkey was signed at Constantinople on September 29, 1913.
Territorial changes as a result of the Second Balkan War moved the Turkish - Bulgarian
boundary westward to the Maritsa. Bulgaria lost Adrianople. Her long vaunted claim to
an outlet on the Aegean became limited to about a seventy mile strip west of the
Maritsa River, which included the port of Dedeagatch.
4. World War I
It is not surprising, therefore, that the Balkan Wars nurtured bitterness and a desire for
vengeance among the Balkan States. Bulgaria found its chance to retaliate by siding
with Turkey and the Central Powers in October 1915. The decision was made easier by
Turkey's cession to Bulgaria of territory around Uskudar (Shtit) and moving the rest of
the 1913 boundary to about one mile east of the Maritsa (Treaty of Sofia, September 6,
1915). Confining her military operations to the Serbian and Greek frontiers, Bulgaria
became the thoroughfare between the Danube and the Bosporus for German
reinforcements to Turkey. Bulgaria was defeated following the final Balkan drive of the
Allied Armies in October 1918.
The Treaty of Neuilly-sur-Seine, November 27, 1919 ended Bulgaria's part in World War
I. As a result, Bulgaria was cut off from the Aegean. An economic outlet in the form of
transit rights through Thrace to the Aegean was ensured by the Allied and Associated
powers. The conditions of the guarantee were to be fixed at a later date. However,
when the subject was raised in the Treaty of Lausanne in 1923, Bulgaria rejected the
offer of transit rights at the port of Dedeagatch (Alexandroupolis).
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B. Physiographic
The Bulgaria - Turkey boundary region is located in the southeastern extremity of the
Balkan Peninsula. From the north on the Bulgarian side, the chief physiographic feature
is a large mountainous area in the shape of a C which faces the Black Sea. The
northern arc of the C which forms the Balkan Range, is also called the Stara Planina.
The western arc consists of the massive Rila Mountains whose highest peak of 9,597
feet is the highest point of East Central Europe. The southern arc forms the Rhodope
Mountains which fan into several broken dissected ranges. Within the arc is the fertile
Rumelian basin drained by the Maritsa River which flows to the Aegean Sea.
On the southern Turkish side of the boundary, the Rhodope form the Istranca
Mountains extending in a broken line southeastward toward the Black Sea. However,
the Istranca, which are generally low lying mountains, gradually rise to form an almost
inaccessible wall parallel to the Black Sea coast as far as the Chatalja Peninsula. On
the southwestern side, the Istranca descend gradually and irregularly toward the Sea of
Marmara and the Aegean. Most of the 9,000 square miles of European Turkey, about 3
percent of the total area of Turkey, is relatively fertile land.
The historic land route between the European heartland and the Orient passes through
intensive agricultural lands of the Maritsa in Bulgaria. Plovdiv (Philippopolis) in the
center of the Maritsa valley, and Sofia the Bulgarian capital are important cities along
this route. The main lines of communication and transport after crossing the tangled
Balkan ranges converge at Edirne (Adrianople) which is near the Greek boundary
tripoint. From there the lines of communication run southeasterly toward Istanbul and
Anatolia.
The chief physical feature of the immediate boundary area is the Istranca mountain
system which is covered with forest, except in the valleys and on the few high peaks.
The trees are chiefly oak and beech and some pine. The bulk of the hill country is
covered only with scrub which is difficult to traverse. On the high slopes, the granite
forms a rough broken surface. The valleys afford some cultivation and pasturage.
Other than several tracks or trails, only one all weather road crosses the boundary in
the northern Istranca. This road which connects Kirklareli, Turkey and Malko Turnovo,
Bulgaria, continues to the Black Sea port of Burgas.
Climate
Climate in the boundary area ranges between continental and Mediterranean. The
Balkan Mountains in the north, standing as a barrier between the northerly winds of the
European continent and the winds from the Mediterranean and the south, affect the
nature of the climate. During the summer months the plains area on the south side,
under the shadow of the Balkans from which warm and dry air currents descend after
depositing much of their moisture on the northern slopes, enjoys a warm sub-tropical
climate.
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The cold, dry conditions which prevail on the Russian steppes in the winter months
frequently extend to the Balkan peninsula, accounting for the moderate rainfall and low
temperature then experienced. Average monthly precipitation during the winter rainy
season is between 3 and 4 inches while that of the dry summer months does not
exceed 2 inches. Temperature ranges between the mean minimum of 36° in January to
the mean maximum of 86° in July or August.
C. Ethnography
Much like the topography, ethnography in the boundary area is marked by complexity
and change. This can be understood readily when one recalls the number and variety of
peoples that have vied with one another. In ancient times the region was inhabited by
Thraco - Illyrians who probably were absorbed by the great Slavic immigrations which
took place in increasing numbers from the third through the seventh centuries. The
Bulgars, although reluctant to concede that Slavs preceded them, are known to have
settled south of the Danube in the seventh century. Like the Huns and the Avars who
preceded them (Goths and other Teutons also preceded them) and like the Magyars
and the Turks who followed them, the Bulgars, classified as Turanian, Mongol, or Tatar,
are of Ural - Altaic origin.
The Ottoman Period
Following the Ottoman Turkish crossing of the Straits in the fourteenth century and the
conquest of the Balkans, the Ottoman social and political pattern was imprinted on the
ethnographic map. During five centuries of Ottoman rule, the map included Bulgar,
Turk, Serb, Macedonian, Greeks, Gypsies, Vlachs, Armenians, Russians, Jews,
Albanians, Circasians and others. The term "Balkanization" is an apt description of this
ethnographic puzzle. Despite its complexity, however, society and politics, inseparable
in Ottoman times, fitted an over-all pattern that could be described as an ethnic mosaic.
While the Empire was in ascendancy, a steady migration of varied peoples from Asian
lands moved into the Balkans and to the outer European boundaries of the Ottoman
Empire. As the Empire declined the migrations reversed direction.
Population figures in Ottoman times vary considerably in validity. However, the 1910
Census estimate for Bulgaria is as follows:
Total Population: 4,337,516
Bulgars 3,203,810 Jews 37,663
Turks 488,010 Armenians 12,270
Rumanian 75,773 Germans 3,863
Gypsies 98,004 Russians 3,275
Greeks 63,487 Others 61,690
Pomaks 26,000
At this time the number of Turks in the Maritsa and Tunca valleys and in eastern
Rumelia was probably about half the total population. The Balkan Wars, however,
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brought about sharp changes in the human landscape in the Bulgaria - Turkey, as well
as the Greek frontier.
Before the outbreak of the Balkan Wars in 1912, the relative proportion of ethnic
grouping in European Turkey, that is, east of the Maritsa and south of the Rezvaya, is
estimated as 65% Turkish, 24% Greek, and about 10% Bulgar. Armenians lived
principally in the larger cities -- perhaps 200,000 in Istanbul (Constantinople), 9,000 at
Adrianople and perhaps 1,000 to 2,000 in a few other cities. In the towns, however,
Turks formed only about one-third of the population, Greeks made up about one-half of
the maritime towns on the Aegean and the Straits. The Bulgars occupied Adrianople,
perhaps 100,000, and extended eastward adjoining the mass of Turkish population.
At the outbreak of the First Balkan War (1912 - 13) most of the Bulgarian population
was driven out of Eastern Thrace, although a few were allowed to remain in Adrianople
and Kirklareli. In addition, about 60,000 of the Greek population, which may have
numbered 200,000 in 1912 emigrated west of the Maritsa by August 1914.
The void caused by emigration became partially filled by immigration of Turks, Pomaks,
and other Muslims from Bulgaria, Macedonia, Albania, and Greece, all territories
formerly part of Ottoman Turkey. In Bulgaria, population increased about 400,000 to
4,753,000 between 1910 and 1914. This two-way movement of population across the
boundary was well under way before World War I, and before the new Turkish Republic
avowed a vigorous policy of Turkification including an aggressive effort to erase all
Ottoman patterns.
More recently, in 1950, the People's Republic of Bulgaria, reflecting the political
tensions existing between the Soviet Bloc and the Free World, expelled 250,000, nearly
one-third of the Turkish population.
The Present Scene
Today, most traces of the ethnographic mosaic of Ottoman times are erased. On the
Turkish side of the boundary, the population based on the census estimate of 1960, is
2,284,621. The area is essentially homogeneous, consisting of Turks, but including the
Turkified Muslims of Bulgarian extraction called Pomaks. The Greek population has
been reduced to about 60,000 Turkish citizens and about 4,000 Greek citizens living in
Istanbul.
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In Bulgaria, the population as of the 1956 census estimate was as follows:
Total Population: 7,613,709
Bulgars 6,506,541
Turks 662,018
Gypsies 197,865
Macedonians 187,789
Armenians 22,000
Russians 10,551
Greeks 7,500
Jews 6,029
Others 13,406
Within proximity of the boundary area itself, the combined population of the three first
order divisions or districts (Okrug) of Burgas, Starazagora, and Khaskovo, all of which
border the Turkish frontier, was 1,666,797. This figure included 1,355,470 Bulgars and
251,831 Turks or a ratio of 5 Bulgars to one Turk.
The Bulgarian Yearbook for 1963 gives the total population for Bulgaria as 8,111,100
and that of the three frontier districts as 1,013,900. A breakdown of population
according to minorities is unavailable.
III. ANALYSIS OF BOUNDARY ALIGNMENT
The Bulgaria - Turkey boundary was last defined in the Treaty of Lausanne of July 24,
1923. With the exception of the fixing of the Greek tripoint, it is as demarcated in 1921
by La Commission de Delimitation de la Frontiere Greco - Bulgare as stipulated in the
Treaty of Neuilly-sur-Seine of November 27, 1919. The entire boundary is essentially
that formed by the Treaty of Constantinople of September 29, 1913, between Bulgaria
and Turkey including the revision according to the Treaty of Sofia of September 6, 1915.
The Treaty of Lausanne confirmed the entire boundary and prescribed the tripoint which
finally was fixed on the Maritsa River by a demarcation commission in 1926.3
The Treaty of Peace between Bulgaria and Turkey (Treaty of Constantinople) of
September 29, 1913 described the boundary as follows:
ARTICLE I. The Frontier
The frontier between the two countries commences at the mouth of the
river Rezvaja, south of the Monastery of San Ivan, which is located on the
Black Sea; it follows the course of this river as far as the confluence of the
rivers Pirogu and Deliva, to the west of Kamila-Koj. Between the mouth
and the point of confluence above-mentioned the river Rezvaja, starting
from its mouth, follows first a southwesterly direction and, leaving Placa to
Turkey, forms a bend and goes towards the northwest and then towards
3
Ibid.
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the southwest; the villages of Madzura and Pirgoplo remain in Ottoman
territory. The river Rezvaja, after having followed a southerly direction
beginning at Pirogoplo and for a distance of approximately five and a half
kilometers, turns towards the west and the north and then goes along,
slightly curved towards the north, in a generally western direction. In this
portion, the villages of Likudi and Kladara remain in Bulgarian territory,
and the villages of Ciknigori, Mavrodio and Lafva return to Turkey; then
the frontier, always following the Rezvaja river, leaves Torfu - Ciflik to
Bulgaria, goes towards the southeast and, leaving the village of Kamila-
Kojin Ottoman territory, arrives at a point about four hundred meters to the
west of this village, at the point of confluence of the rivers Pirogu and
Deliva.
Starting from the junction point of the rivers Pirogu and Deliva, the frontier
line follows the course of the Deliva, and extending along this river in a
general northwesterly direction, leaves the villages of Paspala, Kandildzik
and Deli to Turkey and ends east of Souk - Sou; this last-named village
remains to Turkey, while Seveligu goes to Bulgaria. After having passed
between Souk - Sou and Seveligu, the frontier line continues in a
northwesterly direction, following the ridge which passes over hills 687,
619, and 563; beyond hill 563 it leaves the village of Caglaik (Cajirlik) in
Ottoman territory, and passing around this last village three kilometers to
its east and north, it reaches the Golema stream. The frontier follows the
course of the Golema for a distance of about two kilometers and reaches
the junction point of this stream and the other branch of the same river,
which comes from the south from Karabanlar); beginning at this
confluence the frontier line passes along the ridge to the north of the
stream coming from Turk-Alatli and arrives at the old Turco - Bulgarian
frontier.
The junction point of the new line and the old frontier is four kilometers
east of Turk-Alatli, at the point where the ancient Turco - Bulgarian frontier
forms an angle towards the north in the direction of Aykiri-yol.
Starting at this point it exactly follows the former Turco - Bulgarian frontier
as far as Balaban - Basi west of the Toundja and north of the village of
Derviska - Mog.
At the point where the 1913 boundary crossed the Tunca River, south of the Bulgarian
town of Radovets (Konstantinovo, Tatar-keuy), the line was revised by the Treaty of
Sofia, September 6, 1915. The new line turned southward on the Tunca a distance of
7.5 miles (12 kms.). Markers numbered 279 are placed on both sides of the Tunca
where the boundary follows the river and again double markers numbered 280 where
the line departs from the Tunca. The boundary follows southwestward a distance of 5.4
miles, thence due westward from marker numbered 289 following a distance of six miles
to a tributary of the Kalamitsa river, leaving the towns of Pachama-hale and Uskudar
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(Shtit) to Bulgaria. The boundary follows the Kalamitsa a distance of 5.4 miles to marker
number 315, thence follows a final straight line segment of 3.4 miles southeastward to
terminal marker number 320 and the Greek tripoint on the Maritsa River.
IV. TREATIES AND OTHER ACTS
The following treaties pertain directly to the present Bulgaria - Turkey boundary:
A. Treaty of Peace Between Bulgaria and Turkey, signed at Constantinople,
September 16/29, 1913.
Article I, defines the Bulgaria - Turkey frontier.
The Treaty of Constantinople, and the Treaty of Bucharest, signed on August 10, 1913
between Bulgaria and Greece, Serbia, Rumania, and Montenegro ended the Second
Balkan War.
B. Convention between Bulgaria and Turkey for the Rectification of the Frontier
between the two Countries, signed at Sofia, August 24 (September 6), 1915.
This treaty revised the 1913 boundary by a cession of Turkish territory around Uskudar
to a line about one mile east of the Maritsa River.
C. Treaty of Peace between the Allied and Associated Powers and Bulgaria,
signed at Neuilly-sur-Seine, November 27, 1919.
This treaty defined the boundary according to the Treaty of Constantinople of 1913 and
the Treaty of Sofia of 1915, excluded Bulgaria from the Aegean and provided for the
formation of an international boundary demarcation commission.
D. La Commission de Delimitation de la Frontiere Greco - Bulgare, 1921.
This commission established according to the Treaty of Neuilly, delimited and
demarcated the entire Bulgaria - Turkey boundary.
E. Treaty of Lausanne between Turkey and various Allied Powers, signed at
Lausanne, July 24, 1923.
The Treaty of Lausanne defined the tripoint with Greece, which finally was fixed on the
Maritsa River by a demarcation commission in 1926. The Treaty also confirmed the
boundary as demarcated in 1921.
F. Treaty of Paris, February 10, 1947.
This treaty confirmed all Bulgarian frontiers "which existed on 1 January 1941."
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V. SUMMARY
The Bulgaria - Turkey Boundary is 149 miles (239.5 kms.) in length, comprises 64 miles
in water and 85 miles on land. The entire boundary is demarcated; 320 intervisible
boundary pillars are erected on the segments on land. There are no active disputes
known to exist regarding the specific alignment of the boundary. However, the
possibility of boundary friction persists.
Location of the boundary markers are shown on Sheets 1 through 14 of La Commission
de Delimitation de la Frontiere Greco - Bulgare (Turkiye - Bulgaristan Hududu)
1:25,000, prepared by the official Boundary Commission of 1921. For a large scale
depiction of the boundary, this series is recommended. An accurate representation of
the boundary is found on Army Map Service 1:50,000 scale (Series M-704) Sheets
4378 I, 4378 IV, 4379 III, 4278 I, 4279 II, 4279 III, 4179 II, 4178 I, 4178 IV, 4078 I, and
2624 II (M-708). A small-scale depiction of the boundary on a single sheet (also
includes the Greece - Turkey boundary) is found on Army Map Service 1:1,000,000
scale (series 1301) sheet NK-35.
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This International Boundary Study is one of a series of specific boundary papers
prepared by the Geographer, Office of Research in Economics and Science, Bureau of
Intelligence and Research, Department of State, in accordance with provisions of
Bureau of the Budget Circular No. A-16.
Government agencies may obtain additional information and copies of the study by
calling the Geographer, Room 8744, Department of State, Washington 25, D.C.
(Telephone: Code 182, Extension 4508)
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