You've got an *n* × *m* pixel picture. Each pixel can be white or black. Your task is to change the colors of as few pixels as possible to obtain a barcode picture.

A picture is a barcode if the following conditions are fulfilled: 
 -  All pixels in each column are of the same color. -  The width of each monochrome vertical line is at least *x* and at most *y* pixels. In other words, if we group all neighbouring columns of the pixels with equal color, the size of each group can not be less than *x* or greater than *y*.
The first line contains four space-separated integers *n*, *m*, *x* and *y* (1 ≤ *n*, *m*, *x*, *y* ≤ 1000; *x* ≤ *y*).

Then follow *n* lines, describing the original image. Each of these lines contains exactly *m* characters. Character "." represents a white pixel and "#" represents a black pixel. The picture description doesn't have any other characters besides "." and "#".
dp = {}
h, w, x, y = 0, 0, 0, 0
a = [0] * 1000
def calc(k, s):
  if (k, s) in dp:
    return dp[(k, s)]
  if s > k:
    dp[(k, s)] = 999999999
  elif s >= 1:
    dp[(k, s)] = calc(k - 1, s - 1) + h - a[k]
  elif s == 0:
    dp[(k, 0)] = min([calc(k - 1, 0)] + [calc(k - 1, s0) for s0 in range(x, y + 1)]) + a[k]
  return dp[(k, s)]
h, w, x, y = map(int, input().split())
for i in range(h):
  st = str(input())
  a = [a[i] + (st[i] == '#') for i in range(w)]
dp[(0, 0)] = a[0]
dp[(0, 1)] = h - a[0]
ans = 999999999
for s in range(0, y + 1):
  g = calc(w - 1, s)
  if s == 0 or x <= s <= y:
    ans = min(ans, g)
print(ans)
dp = {}
h, w, x, y = 0, 0, 0, 0
a = [0] * 1000
def calc(k, s):
  if (k, s) in dp:
    return dp[(k, s)]
  if s > k:
    dp[(k, s)] = 999999999
  elif s >= 1:
    dp[(k, s)] = calc(k - 1, s - 1) + h - a[k]
  elif s == 0:
    dp[(k, 0)] = min([calc(k - 1, 0)] + [calc(k - 1, s0) for s0 in range(x, y + 1)]) + a[k]
  return dp[(k, s)]
h, w, x, y = map(int, input().split())
for i in range(h):
  st = str(input())
  a = [a[i] + (st[i] == '#') for i in range(w)]
dp[(0, 0)] = a[0]
dp[(0, 1)] = h - a[0]
ans = 999999999
for s in range(0, y + 1):
  g = calc(w - 1, s)
  if s == 0 or x <= s <= y:
    ans = min(ans, g)
print(ans)
