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: ['7115', '7851', 'p', 'S', '5097', '9101', 'z', 'O', 'e', '2107', '7991', 'n', '1415', 'M', '4039', '8563', 'f', 'P']

7115, 7851, 16, 19, 5097, 9101, 26, 15, 5, 2107, 7991, 14, 1415, 13, 4039, 8563, 6, 16