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: ['9475', 'U', 'C', 'p', 'a', 'k', '3687', '9245', 'R', 'D', '4953', '2113']

9475, 21, 3, 16, 1, 11, 3687, 9245, 18, 4, 4953, 2113