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', '3581', '509', 'C', 'D', 'R', 'e', '6161', '9363', '7443', '321', '7139', '3761', 'Z', 'H', '5077', 'n', '1477', '8921', 's', 'f', 'r', '3319', '1793', 'd', '2551', 'n', 'L', '1235', '6147', 'Z', 'm', 's', 't', 'I', '9367', 's']

21, 3581, 509, 3, 4, 18, 5, 6161, 9363, 7443, 321, 7139, 3761, 26, 8, 5077, 14, 1477, 8921, 19, 6, 18, 3319, 1793, 4, 2551, 14, 12, 1235, 6147, 26, 13, 19, 20, 9, 9367, 19