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: ['6551', 'G', 'k', 'y', '6197', '1639', 'J', '3249', 'b', 'I', 'y', 's', 'u', 'y', 'h', '1255']

6551, 7, 11, 25, 6197, 1639, 10, 3249, 2, 9, 25, 19, 21, 25, 8, 1255