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: ['8643', 'H', 'g', '7997', '4131', 'c', '7125', 'Z', '2811', '3543', '269', 'Y', 'E', 'R', 'A', '2241', 'G', '9967', '3141', 'B', 'Y', 'A', '3263', 'c', '251', 'D', 'z', '5509', '1805']

8643, 8, 7, 7997, 4131, 3, 7125, 26, 2811, 3543, 269, 25, 5, 18, 1, 2241, 7, 9967, 3141, 2, 25, 1, 3263, 3, 251, 4, 26, 5509, 1805