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: ['6937', '6847', 'z', '8147', 'o', '4115', 'a', 'X', '7491', '7733', '725', 'g', 's', '4139', '5737', 'M', '2985', '4743', '6549', 'B', 'N', 'G', 'c', 'b', '6323', 'u', '2839', 'l', 'u', 'W', 'p', '9927', 'p', 'C', '8083', 'i', 't', '8927', '9431']

6937, 6847, 26, 8147, 15, 4115, 1, 24, 7491, 7733, 725, 7, 19, 4139, 5737, 13, 2985, 4743, 6549, 2, 14, 7, 3, 2, 6323, 21, 2839, 12, 21, 23, 16, 9927, 16, 3, 8083, 9, 20, 8927, 9431