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', '353', '6555', '721', '8481', '9423', '2789', '2473', '3843', 'Q', '4979', 'Z', 'g', 'W', '2901', 'z', 'i', '9641', '7531', 'v', 'D', 'Z']

21, 353, 6555, 721, 8481, 9423, 2789, 2473, 3843, 17, 4979, 26, 7, 23, 2901, 26, 9, 9641, 7531, 22, 4, 26