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: ['u', 'S', '7579', 's', '8739', 'x', '4179', '3443', '5587', 'z', '6605', 'D']

21, 19, 7579, 19, 8739, 24, 4179, 3443, 5587, 26, 6605, 4