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: ['6711', 'S', '8637', 'm', '1251', '7971', '2435', '8143', '4505', '4285', 'a', 'i', 'P', '9701', '643', '7659', 'r', 'C', '1861', '7915', 'L', 'z', 'z']

6711, 19, 8637, 13, 1251, 7971, 2435, 8143, 4505, 4285, 1, 9, 16, 9701, 643, 7659, 18, 3, 1861, 7915, 12, 26, 26