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: ['S', '5901', '8535', 'O', '6213', '621', 'l', 'C', '4577', 'Y', 'y', 'm', 'D', '1839', '9939', '9271', '1441', 'L', 'J', '9887', '3321', '9189', '9821']

19, 5901, 8535, 15, 6213, 621, 12, 3, 4577, 25, 25, 13, 4, 1839, 9939, 9271, 1441, 12, 10, 9887, 3321, 9189, 9821