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: ['S', 'y', '3991', 'W', 'A', 'z', 'V', 'v', '8871', '2495', 'M']

19, 25, 3991, 23, 1, 26, 22, 22, 8871, 2495, 13