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: ['4775', '2837', 'l', '5187', '9259', 'L', '6423', '183', 'i', 'q', 'r', 'U', '7415', 'c', '883', 'x']

4775, 2837, 12, 5187, 9259, 12, 6423, 183, 9, 17, 18, 21, 7415, 3, 883, 24