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: ['9271', 'l', 'r', '3649', 'w', '6819', 'C', 'w', 'B', '7123', '8913', 'S', '8941', '1489', 'a', 'X', '3951']

9271, 12, 18, 3649, 23, 6819, 3, 23, 2, 7123, 8913, 19, 8941, 1489, 1, 24, 3951