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', '8019', 's', 'n', 'U', 'N', '4587', 'p', 'P', 'w', '6275', 'Q', 'p', '1539', 'H', '6085', 't', 'c', 'V', '7639']

21, 8019, 19, 14, 21, 14, 4587, 16, 16, 23, 6275, 17, 16, 1539, 8, 6085, 20, 3, 22, 7639