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', '9453', 'O', 'M', 'A', 'y', 't', '7169', 'Q', 'l', '8669', '867']

15, 9453, 15, 13, 1, 25, 20, 7169, 17, 12, 8669, 867