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: ['9597', 'O', 'T', 'U', 'y', 's', '4749', 'r', '6571', '5431', '2503', 'P', '4513', '5025', 't', '9045', '7997', '3329', 'R']

9597, 15, 20, 21, 25, 19, 4749, 18, 6571, 5431, 2503, 16, 4513, 5025, 20, 9045, 7997, 3329, 18