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: ['2973', 'a', '6251', 's', '5009', 'm', 'G']

2973, 1, 6251, 19, 5009, 13, 7