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: ['5389', 'm', 'S', '2019', '5447', 'y', '527', 'y', '6691', '855', '4873', 'H', 'M', 'S', 'X', 'm', '6143']

5389, 13, 19, 2019, 5447, 25, 527, 25, 6691, 855, 4873, 8, 13, 19, 24, 13, 6143