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', '8551', 'Z', '9923', '647', '8747', '7707', 'o', '7117', 'p', 'r', '6161', 'L', '5993', '6717', '2885', '9289', '6517', 'v', 'H', '3055', 'U', 'Q', '7569', '4495']

21, 8551, 26, 9923, 647, 8747, 7707, 15, 7117, 16, 18, 6161, 12, 5993, 6717, 2885, 9289, 6517, 22, 8, 3055, 21, 17, 7569, 4495