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', 'P', 'n', 'P', '537', '6431', 'u', 'Y']

21, 16, 14, 16, 537, 6431, 21, 25