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: ['5907', '509', 'd', '8947', 'i', '2539', '7059', 'N', '5201', '3373', 'I', 'M', 'a', '7427', '3259', 'm', '6247', '4645', 'H']

5907, 509, 4, 8947, 9, 2539, 7059, 14, 5201, 3373, 9, 13, 1, 7427, 3259, 13, 6247, 4645, 8