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: ['U', 'P', '1595', '9935', '8445', '8137', 'B', '9773', '3475', '5207', '2637', '9883', '9845', '3529', 'U', 'u', 'F', '4775']

21, 16, 1595, 9935, 8445, 8137, 2, 9773, 3475, 5207, 2637, 9883, 9845, 3529, 21, 21, 6, 4775