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: ['O', '9639', 'J', '5291', '769', 'j', 'P', '6133', 'j', '7961', 't', 'e', 'D', '7683', 't', '2005', 'b', 'M', 'N', 'S', '8075', '325', 'e', '2127', '4295', '921', 'R', 'a', '3233', 'o', '6545', 'a', '4205', '8709', '1803', 'F', 'I']

15, 9639, 10, 5291, 769, 10, 16, 6133, 10, 7961, 20, 5, 4, 7683, 20, 2005, 2, 13, 14, 19, 8075, 325, 5, 2127, 4295, 921, 18, 1, 3233, 15, 6545, 1, 4205, 8709, 1803, 6, 9