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: ['O', 'i', 'F', 'C', '3513', 'q', 'w', '9783', '5317', '8081', '8495', 't', '4559', '6057', '5655', 'S', '1993', '6091', 'r', 'O', 'A', 'C', 'M']

15, 9, 6, 3, 3513, 17, 23, 9783, 5317, 8081, 8495, 20, 4559, 6057, 5655, 19, 1993, 6091, 18, 15, 1, 3, 13