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: ['1289', 'b', 'o', '1311', '2155', '5965', 'C', 't', '8375', '2739', 'U', '7393', 'c', 'R', '729', 'L', '9797', '7483', '6731', '7047', 'x', '7579', '8283', '3889', 'G', '3127', 'r', 'g', 'u', 'B']

1289, 2, 15, 1311, 2155, 5965, 3, 20, 8375, 2739, 21, 7393, 3, 18, 729, 12, 9797, 7483, 6731, 7047, 24, 7579, 8283, 3889, 7, 3127, 18, 7, 21, 2