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', 'f', '5335', 'E', '5907', '1207', '3417', '2111', '4809', 'J', '7175', '9781', '5171', '5735', '4921', 'm', 'j', 'k', 'O', '6935', 'e', '4663', '1793', '8179', 'F', 'f', 'S', '6539']

15, 6, 5335, 5, 5907, 1207, 3417, 2111, 4809, 10, 7175, 9781, 5171, 5735, 4921, 13, 10, 11, 15, 6935, 5, 4663, 1793, 8179, 6, 6, 19, 6539