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: ['2559', 's', '9887', 'c', '1459', '3937', 'z', 'D', 'A', 'k', 'I', '6239', 'U', '7029', 'B', '5279', '4435', '4285', '9007', '9987', '747', 'O', '2675', '1019', 'K', 'r']

2559, 19, 9887, 3, 1459, 3937, 26, 4, 1, 11, 9, 6239, 21, 7029, 2, 5279, 4435, 4285, 9007, 9987, 747, 15, 2675, 1019, 11, 18