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: ['879', 'c', '3969', '2467', '2683', 'P', '2639', '3973', '587', 'E', '9035', '5979', '613', 'o', 'F']

879, 3, 3969, 2467, 2683, 16, 2639, 3973, 587, 5, 9035, 5979, 613, 15, 6