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: ['a', 'T', 'R', '6471', 'r', '4869', '821', 'Y', '9341', '1983', '965', 'o', '3099', '6809', 's', '9913', '9307', '8031', 'b', '4221', 'l', '8275', '7723', '2059']

1, 20, 18, 6471, 18, 4869, 821, 25, 9341, 1983, 965, 15, 3099, 6809, 19, 9913, 9307, 8031, 2, 4221, 12, 8275, 7723, 2059