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: ['R', 't', 'u', '7291', '9549', '6063', '4255', 'w', 'r', '9611', 'k', 's']

18, 20, 21, 7291, 9549, 6063, 4255, 23, 18, 9611, 11, 19