C. Barcodetime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou'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. InputThe 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 "#".OutputIn the first line print the minimum number of pixels to repaint. It is guaranteed that the answer exists. ExamplesInput6 5 1 2##.#..###.###..#...#.##.####..Output11Input2 5 1 1#####.....Output5NoteIn 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:  .#.#..#.#. 
Input6 5 1 2##.#..###.###..#...#.##.####..
Output11
['dp', 'matrices', '*1700']