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: ['6787', 'm', 'z', '9209', 'J', 'A', 'l', '7445', 'x', 'R', 'X', '369', 'c', 'r', 'M', 'v', '2573', 'o', 'G', 'C', '3499', '8147', 'A']

6787, 13, 26, 9209, 10, 1, 12, 7445, 24, 18, 24, 369, 3, 18, 13, 22, 2573, 15, 7, 3, 3499, 8147, 1