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', '9637', 'k', 'T', '8897', 'G', 'D', 'D', 'J', 'a', '9891', 'V', '3867', 'R']

21, 9637, 11, 20, 8897, 7, 4, 4, 10, 1, 9891, 22, 3867, 18