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: ['O', '6731', '8543', 's', '5535', '9215', 'c', '8963', '4095', 'W', 'r', '8965', 'p', '9003', '9453', '5329', 'p', 'S', 'j', '1187', '281', '7429', '843', 'J', '4685', '913', 'p', 't', 'D', '2981', '6999', '2839', 'c', 'G']

15, 6731, 8543, 19, 5535, 9215, 3, 8963, 4095, 23, 18, 8965, 16, 9003, 9453, 5329, 16, 19, 10, 1187, 281, 7429, 843, 10, 4685, 913, 16, 20, 4, 2981, 6999, 2839, 3, 7