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: ['7409', 'o', '431', '6415', 'J', 'N', 'm', '9753', 'u', 'H', 'x', '6001', '3643', 'Q', 'b']

7409, 15, 431, 6415, 10, 14, 13, 9753, 21, 8, 24, 6001, 3643, 17, 2