B'You 've got an n xe2 x80 x89 xc3 x97 xe2 x80 x89m 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: The first line contains four space-separated integers n, m, x and y (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n, xe2 x80 x89m, xe2 x80 x89x, xe2 x80 x89y xe2 x80 x89 xe2 x89 xa4 xe2 x80 x891000; x xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89y). 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 "#". In the first line print the minimum number of pixels to repaint. It is guaranteed that the answer exists. In the first test sample the picture after changing some colors can looks as follows: In the second test sample the picture after changing some colors can looks as follows: '...