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: ['5219', 'S', 'q', 'P', 't', 'L', 't', 'P', '7909', '6139', '5623', 'w', 'l', '1681', 'R', '8019', '3765', 'M', 'J', '7145', 'u', '6789', 'T', '1257']

5219, 19, 17, 16, 20, 12, 20, 16, 7909, 6139, 5623, 23, 12, 1681, 18, 8019, 3765, 13, 10, 7145, 21, 6789, 20, 1257