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: ['6509', '893', '7993', 'r', 'U', '2431', 'O', '1211', '5529', '723', '5937', 'O', '8369', 'e', '7907', 'y', '1591', '3171', '9375', 'N', 'z', 'v', 'L', 'J', 'l', '3523', 'T', 'R']

6509, 893, 7993, 18, 21, 2431, 15, 1211, 5529, 723, 5937, 15, 8369, 5, 7907, 25, 1591, 3171, 9375, 14, 26, 22, 12, 10, 12, 3523, 20, 18