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: ['1043', '2917', 'u', '8921', 'O', '545', '315', '7209', '8749', 'u', 'e', 'C', 'F', 'z', '3483', 'R', '3503', 'y', 'w', '2759']

1043, 2917, 21, 8921, 15, 545, 315, 7209, 8749, 21, 5, 3, 6, 26, 3483, 18, 3503, 25, 23, 2759