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: ['9787', 'P', '207', 'c', 'S', '2695', 'U', 'b', 'f', 'D', 'g', 'C', 'f', 'L', '7639', '6277', '2801', '1047', '9231']

9787, 16, 207, 3, 19, 2695, 21, 2, 6, 4, 7, 3, 6, 12, 7639, 6277, 2801, 1047, 9231