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: ['X', 't', 'P', 'u', '9403', 'p', '2301', '557', 'U', 'a', 'q', '1699', 'I', '2453', '513', '5625', '1603', '2469', '8043', '8253', 'X', '3851', '4015']

24, 20, 16, 21, 9403, 16, 2301, 557, 21, 1, 17, 1699, 9, 2453, 513, 5625, 1603, 2469, 8043, 8253, 24, 3851, 4015