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: ['9507', 'S', '7067', '1683', 'v', '7839', '7933', '7349', '3243', 'b', 'O', '339']

9507, 19, 7067, 1683, 22, 7839, 7933, 7349, 3243, 2, 15, 339