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: ['U', '9191', '4245', 'i', '53', '5465', '4121', 'v', 'b', 'n', 'l', 't', 'X', '4675', 'U', '5139', 'J', 'a', 'r', '3573', 'a', 'M', 'C', '3957', 'r', '2115', 'r', '2727', '8295', '6013', '1789', 'B', 'H', '7459', 'N', 'A', 'H', 'X', 'y']

21, 9191, 4245, 9, 53, 5465, 4121, 22, 2, 14, 12, 20, 24, 4675, 21, 5139, 10, 1, 18, 3573, 1, 13, 3, 3957, 18, 2115, 18, 2727, 8295, 6013, 1789, 2, 8, 7459, 14, 1, 8, 24, 25