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: ['4903', '6945', 'r', 'E', '831', '8917', 'u', '7685', '6835', 'p', '3097', '5425', 'f']

4903, 6945, 18, 5, 831, 8917, 21, 7685, 6835, 16, 3097, 5425, 6