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: ['7511', 'c', '5999', 'j', '2265', 'E', '9905', '1861', '8743', '873']

7511, 3, 5999, 10, 2265, 5, 9905, 1861, 8743, 873