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: ['2129', 'f', 'm', '1815', '7325', 'd', 'C', 'M', '9867']

2129, 6, 13, 1815, 7325, 4, 3, 13, 9867