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: ['6877', 'C', '9173', 'n', '7545', '1913', 'b', '9463', '5311', 'y', 'Z', '2947', 'U', 'B', '7275', '6791', '5117', '4183', 'r', '15', 'l', '405', 'd', '213', '8955', 'o', '7355', '5323', '2489']

6877, 3, 9173, 14, 7545, 1913, 2, 9463, 5311, 25, 26, 2947, 21, 2, 7275, 6791, 5117, 4183, 18, 15, 12, 405, 4, 213, 8955, 15, 7355, 5323, 2489