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: ['6353', 'f', '6269', '463', '7553', 'i', '5549', 'k', '539', '9165', 'z', '1503', 'p', 'i', 'A', '5487', '6861', 'S', 'R', '2289', 'w', '6337', 't', 'u']

6353, 6, 6269, 463, 7553, 9, 5549, 11, 539, 9165, 26, 1503, 16, 9, 1, 5487, 6861, 19, 18, 2289, 23, 6337, 20, 21