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: ['9739', 'R', '7987', '1317', 'v', '611', '6553', '4745', '8561', '5555', 'Y', 'C']

9739, 18, 7987, 1317, 22, 611, 6553, 4745, 8561, 5555, 25, 3