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: ['s', 'k', 'D', 'b', 'y', '5243', 'f', '9499', '6043', 'G', '6951', 'K', '4425', '7321', 'N', '6469', '999', '3333', 'D']

19, 11, 4, 2, 25, 5243, 6, 9499, 6043, 7, 6951, 11, 4425, 7321, 14, 6469, 999, 3333, 4