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: ['L', 'O', 'm', 'P', 't', '6991', 'g', '1681', 'B', 'X', 'n', 'u', 'L', 'Q', 'l', '6717', '1303', 'o', '8615', '9761', 'F', '1397', 'e', 'u']

12, 15, 13, 16, 20, 6991, 7, 1681, 2, 24, 14, 21, 12, 17, 12, 6717, 1303, 15, 8615, 9761, 6, 1397, 5, 21