Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['r', '1555', '1875', 'W', '1295', '6513', 'M', '8051', '8949', 'y', 'O', '1929', '25', '2495', 'o', '2049', '2751', '7287', '531', '3215', 'S', 'W', 'O', '4165', '3309']

18, 1555, 1875, 23, 1295, 6513, 13, 8051, 8949, 25, 15, 1929, 25, 2495, 15, 2049, 2751, 7287, 531, 3215, 19, 23, 15, 4165, 3309