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: ['7787', 'Z', '9537', '4685', '5857', '5919', 'y', 'O', '165', 'z', 'O', '1427', '6539', 's', 'x', 'c', 'M', '6897', '4755', 'o']

7787, 26, 9537, 4685, 5857, 5919, 25, 15, 165, 26, 15, 1427, 6539, 19, 24, 3, 13, 6897, 4755, 15