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: ['5671', 'O', 'r', '2473', '9907', '9515', '9817', 'E', '5479', 'G', '6493', '7015']

5671, 15, 18, 2473, 9907, 9515, 9817, 5, 5479, 7, 6493, 7015