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: ['z', 'z', '6155', '9681', '7583', 'P', 'r', 'l', 's', '7821', '8573', '5821']

26, 26, 6155, 9681, 7583, 16, 18, 12, 19, 7821, 8573, 5821