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: ['7991', 'k', 'A', 'J', 'c', 'H', 'i', 'o']

7991, 11, 1, 10, 3, 8, 9, 15