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: ['6191', 'x', '8897', '3451', '6273', 'W', '2433', 'E', 'b', 'u', 'W', 'O', 'L', 'D', '4311', '2441', 'U', 's', 'K']

6191, 24, 8897, 3451, 6273, 23, 2433, 5, 2, 21, 23, 15, 12, 4, 4311, 2441, 21, 19, 11