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', '3315', 'A', 'j', 'r', 'B', 'k', 'r', '9813', '1197', 'D', '1323', '4575', 'l', '4449', '855', 'e', '6409', 'W', '7533', 'l', '171', '9453']

21, 3315, 1, 10, 18, 2, 11, 18, 9813, 1197, 4, 1323, 4575, 12, 4449, 855, 5, 6409, 23, 7533, 12, 171, 9453