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: ['2697', 'U', 'O', '8891', '5143', 'f', 'Q', '689', 'g', '5873', 'r', '9041', '1337', '8981', 'm', 'o', '5403', '7719']

2697, 21, 15, 8891, 5143, 6, 17, 689, 7, 5873, 18, 9041, 1337, 8981, 13, 15, 5403, 7719