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: ['5251', '1929', 'x', 's', '4319', '9571', '2147', 'P', 'g', 'k', 'H', '3913']

5251, 1929, 24, 19, 4319, 9571, 2147, 16, 7, 11, 8, 3913