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: ['6517', '5837', 'P', '53', 'U', 'j', '1615', 'K', 'U', 'g', '4821', '7777', 'G', 'y', 'D', 'N', 'A', '4047', '2261']

6517, 5837, 16, 53, 21, 10, 1615, 11, 21, 7, 4821, 7777, 7, 25, 4, 14, 1, 4047, 2261