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: ['1051', '4899', '2449', '3161', 'J', 'L', 'O']

1051, 4899, 2449, 3161, 10, 12, 15