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', 'j', 'I', '4239', '7197', '4139', 'v', '6255', '8017', 'I', '5893', 'y', '7721', '6973']

23, 10, 9, 4239, 7197, 4139, 22, 6255, 8017, 9, 5893, 25, 7721, 6973