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: ['5143', '7407', '9581', 's', '8431', '5397', 'A', 'y', '1503', 'R', '2109', '8793', 'T', '5917', 'G', 'S', 'J', '9221', 'u', 'k', '4025', 'z']

5143, 7407, 9581, 19, 8431, 5397, 1, 25, 1503, 18, 2109, 8793, 20, 5917, 7, 19, 10, 9221, 21, 11, 4025, 26