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: ['W', '1639', '3211', 'X', '5573', '5653', '6851', '601', '8953', '5415', 'a', 'c']

23, 1639, 3211, 24, 5573, 5653, 6851, 601, 8953, 5415, 1, 3