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: ['n', 'A', '3405', 'm', '8623', 'G', '9407', '8427', '1969']

14, 1, 3405, 13, 8623, 7, 9407, 8427, 1969