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: ['u', '5261', '3889', 'a', '4683', 'L', 'Z', 'U', 'E']

21, 5261, 3889, 1, 4683, 12, 26, 21, 5