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: ['6261', 'A', 'H', '8137', '6447', 'd', 'U', 'z', 'v', '5819', 'l', 'Q', '9421', 'z', '1297', 'G', 'G', '8607', '671', 't', 'y', '5051', '9133']

6261, 1, 8, 8137, 6447, 4, 21, 26, 22, 5819, 12, 17, 9421, 26, 1297, 7, 7, 8607, 671, 20, 25, 5051, 9133