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: ['2557', '6147', '8503', '7647', 'D', 'a', 'u', '3173', 'K', 'L', '1331', 'W', '5033', '1127', '4717', '8353', '5637', '2881', 'j', 'K', 'Q', '6821', '8307', '6875', '9481', '5585', '1645', 'N', '6199', 'O', 'i', '6731', '4913', 'I', '2833']

2557, 6147, 8503, 7647, 4, 1, 21, 3173, 11, 12, 1331, 23, 5033, 1127, 4717, 8353, 5637, 2881, 10, 11, 17, 6821, 8307, 6875, 9481, 5585, 1645, 14, 6199, 15, 9, 6731, 4913, 9, 2833