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: ['u', '573', 'J', '1931', '8527', '2045', '1439', '3147', 'O', 'q', 'S', '2139', '4379', 'V', 'D', '9739', 'H', 'C', 'a', '747', 'm', '8227', '6823', 'f', '5685', 'y', 'd', 'z', '9639', 'x', 'u']

21, 573, 10, 1931, 8527, 2045, 1439, 3147, 15, 17, 19, 2139, 4379, 22, 4, 9739, 8, 3, 1, 747, 13, 8227, 6823, 6, 5685, 25, 4, 26, 9639, 24, 21