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: ['4235', 'l', '4951', 'P', 'L', 'B', 'R', '5919', '5261', 'M', 'l', '9775', '9221', '143', 'i', 'f']

4235, 12, 4951, 16, 12, 2, 18, 5919, 5261, 13, 12, 9775, 9221, 143, 9, 6