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: ['M', 'r', '1931', 'q', '9475', 'n', '4891', '3129', 'C', '3961', '57', '7923']

13, 18, 1931, 17, 9475, 14, 4891, 3129, 3, 3961, 57, 7923