H, W, K, V = gets.chomp.split.map(&:to_i)

A = []

H.times do

A << gets.chomp.split.map(&:to_i)

end

def cumsum_2d(arr)

h = arr.length

w = arr[0].length

arr.unshift(Array.new(w, 0))

arr.each { |line| line.unshift(0) }

cumsum = Array.new(h + 1) { Array.new(w + 1, 0) }

1.upto(h) do |i|

cumsum[i][j] += arr[i][j] + cumsum[i - 1][j] + cumsum[i][j - 1] - cumsum[i - 1][j - 1]

end

1.upto(h) do |i|

1.upto(w) do |j|

cumsum[i][j] += arr[i][j] + cumsum[i - 1][j] + cumsum[i][j - 1] - cumsum[i - 1][j - 1]

end

end

cumsum

end

cumsum = cumsum_2d(A)

area = 0

1.upto(W) do |w|

1.upto(H) do |h|

1.upto(W) do |j|

1.upto(H) do |i|

next if i + h > H + 1 || j + w > W + 1

tochi = cumsum[i + h - 1][j + w - 1] - cumsum[i - 1][j + w - 1] - cumsum[i + h - 1][j - 1] + cumsum[i - 1][j - 1]

kensetsu = w * h * K

next if tochi + kensetsu > V

area = [area, w * h].max

end

end

end

end

puts area