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: ['J', 'O', '673', '5721', '621', '8095', '5063', 'r', '1285', '4895', 'Z', '9789', 'J', '6549', '57', '9021', 'P', '9637', '8415']

10, 15, 673, 5721, 621, 8095, 5063, 18, 1285, 4895, 26, 9789, 10, 6549, 57, 9021, 16, 9637, 8415