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: ['6827', '5603', 'S', 'x', 'f', '5513', '5721', 'c', '249', 'M', 'N', '8317', 'F', '5775', '895', '5617', '3669', '3393', '9319', '871']

6827, 5603, 19, 24, 6, 5513, 5721, 3, 249, 13, 14, 8317, 6, 5775, 895, 5617, 3669, 3393, 9319, 871