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: ['5135', 'f', 'D', 'J', '8465', '5769', '1117', 'T', '4055', 'b', 'f', 'l', 'l', '9439', '7601', 's', 'u', '9853']

5135, 6, 4, 10, 8465, 5769, 1117, 20, 4055, 2, 6, 12, 12, 9439, 7601, 19, 21, 9853