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: ['o', 'n', '7571', 'c', '245', '2745', 'u', 'Z', '9353', '3907', '6869', '1993', 's', '279', '3603', '5971', '1621', '4601', '3603']

15, 14, 7571, 3, 245, 2745, 21, 26, 9353, 3907, 6869, 1993, 19, 279, 3603, 5971, 1621, 4601, 3603