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: ['N', 'p', 'n', '7253', 'e', '9687', '659', 'U', 'Q', '2015', '4637', 'Y', 'H', 'l', '9131', 'n', '6253', '8387', 'U', '9555', 'm']

14, 16, 14, 7253, 5, 9687, 659, 21, 17, 2015, 4637, 25, 8, 12, 9131, 14, 6253, 8387, 21, 9555, 13