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: ['1909', 'X', 'W', 'W', '827', 'O', 'F', '4629', '7931', 'l', 'G', 'Z', 'r']

1909, 24, 23, 23, 827, 15, 6, 4629, 7931, 12, 7, 26, 18