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: ['L', 'M', '9547', '9787', 'C', '6993', '5623', 'N', 'x', '3495', '6071', '5413', 'Y', '5191', '9621', 'X', '8557', '7949', '5691', 'u', '7527', '621', '6899', 'E', 'K', 'a']

12, 13, 9547, 9787, 3, 6993, 5623, 14, 24, 3495, 6071, 5413, 25, 5191, 9621, 24, 8557, 7949, 5691, 21, 7527, 621, 6899, 5, 11, 1