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: ['U', '2449', '123', '8839', '2957', '6807', '6569', 'l', '1379', 'p', 'D', '2577', '1429', 'N', 'x', 'B', '9109', '9301', 'P', 'Q', 'r', 'Y', 'w', '7565', '473', 'k', '5047', '6329', 'D', '1385', '3039', '2535', '9973', '4849', 'r', 'v', 'R', '269', '6741', 'n']

21, 2449, 123, 8839, 2957, 6807, 6569, 12, 1379, 16, 4, 2577, 1429, 14, 24, 2, 9109, 9301, 16, 17, 18, 25, 23, 7565, 473, 11, 5047, 6329, 4, 1385, 3039, 2535, 9973, 4849, 18, 22, 18, 269, 6741, 14