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: ['5729', '3907', '8541', '3261', 'f', '8225', 'u', 'L', 'f', 'k', 'a', '6755']

5729, 3907, 8541, 3261, 6, 8225, 21, 12, 6, 11, 1, 6755