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: ['H', 'k', 'C', '7943', 'R', 'I', '7181', '1271', '9711', '2579', '8613', 'l', '859', '5751', '6531', '3583']

8, 11, 3, 7943, 18, 9, 7181, 1271, 9711, 2579, 8613, 12, 859, 5751, 6531, 3583