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: ['1913', 's', '7439', 'B', 'l', '6141', 'O', '3319', 'y', '5013', 'c', 'R', '6779', 'G', '4105', '9243']

1913, 19, 7439, 2, 12, 6141, 15, 3319, 25, 5013, 3, 18, 6779, 7, 4105, 9243