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: ['x', 'C', 'J', 'S', 's', '6239', 'x', '9455', '4115', 'I', 't', '5457', '5719', 'u', 'S', '8141', '4343', 'V', 'H']

24, 3, 10, 19, 19, 6239, 24, 9455, 4115, 9, 20, 5457, 5719, 21, 19, 8141, 4343, 22, 8