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: ['6007', '2261', '5631', 'U', 'L', 'u', '1791', '1307', 'w', '6539', 'm', '1061', '3589']

6007, 2261, 5631, 21, 12, 21, 1791, 1307, 23, 6539, 13, 1061, 3589