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', '1877', 'v', 'R', 'K', 'Q', '7461', '499', 'v', '6581', '9129', '5907', '5561', 'K', '2063', 'w', 'a', '2833', 'U', 'C']

19, 1877, 22, 18, 11, 17, 7461, 499, 22, 6581, 9129, 5907, 5561, 11, 2063, 23, 1, 2833, 21, 3