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', 'Z', '9581', 'F', 'G', 'u', 'N', 'M', 'l', '1463', '4963', '5903', 'K', '7999', 's', 'E', 'q', '297', 'j', '8315', 'x', '5331', '5379', 'R']

21, 26, 9581, 6, 7, 21, 14, 13, 12, 1463, 4963, 5903, 11, 7999, 19, 5, 17, 297, 10, 8315, 24, 5331, 5379, 18