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: ['2515', 'a', 'e', 'n', '281', 'I', 'S', '8307', '3617', '6139', 'H', 'L', 'J', '4055', '9429', '5329', '9301', '2151', '5207', '1449', '4825', 'B', '7715', '4913', 'N', 'U', '9125', 'Y', '4343', 'R', 'x', 'f', '8727', '4801', 'G', 'x', '1377', '857', 'R', 'O']

2515, 1, 5, 14, 281, 9, 19, 8307, 3617, 6139, 8, 12, 10, 4055, 9429, 5329, 9301, 2151, 5207, 1449, 4825, 2, 7715, 4913, 14, 21, 9125, 25, 4343, 18, 24, 6, 8727, 4801, 7, 24, 1377, 857, 18, 15