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: ['a', 'f', 'k', '2457', 'l', 'P', 'b', '7883', '3743']

1, 6, 11, 2457, 12, 16, 2, 7883, 3743