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: ['3287', 's', 'g', '5017', '2327', '2779', '985', 'b', 'H', '6211', '9309', '2509', 'Z', 'a', 'u', '7657', '5131', 'O', '4335', 'U', '7429', 'R']

3287, 19, 7, 5017, 2327, 2779, 985, 2, 8, 6211, 9309, 2509, 26, 1, 21, 7657, 5131, 15, 4335, 21, 7429, 18