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: ['21', '9491', 'l', '8591', 'V', 'O', '9709', '5371', 'x', '8367', '6205', '9941', '1209', '695', 'E', 'H', '4457', 'K', 'l']

21, 9491, 12, 8591, 22, 15, 9709, 5371, 24, 8367, 6205, 9941, 1209, 695, 5, 8, 4457, 11, 12