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: ['1841', '5149', 'S', '9607', '4699', '9195', '7507', '7669', '8195', '6411', '5953', '411', 'T', '3669', 'X', 'U', '715']

1841, 5149, 19, 9607, 4699, 9195, 7507, 7669, 8195, 6411, 5953, 411, 20, 3669, 24, 21, 715