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 "#".
def calculate_repaint_count(n, m, x, y, pixels):
    repaint_count = 0

    for col in range(m):
        consecutive_count = 1
        current_color = pixels[0][col]

        for row in range(1, n):
            if pixels[row][col] != current_color:
                if consecutive_count < x:
                    repaint_count += x - consecutive_count
                elif consecutive_count > y:
                    repaint_count += consecutive_count - y

                current_color = pixels[row][col]
                consecutive_count = 1
            else:
                consecutive_count += 1

        if consecutive_count < x:
            repaint_count += x - consecutive_count
        elif consecutive_count > y:
            repaint_count += consecutive_count - y

    return repaint_count

# Read the input values
n, m, x, y = map(int, input().split())
pixels = [list(input()) for _ in range(n)]

# Calculate the minimum number of pixels to repaint
result = calculate_repaint_count(n, m, x, y, pixels)

# Print the result
print(result)
