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: ['S', 'D', '6375', '59', '8823', 's', '2591', '3923', '351', 'z', 'm', '1257', '1239', 'm', '2945', 'E']

19, 4, 6375, 59, 8823, 19, 2591, 3923, 351, 26, 13, 1257, 1239, 13, 2945, 5