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: ['3909', '5955', 'D', '6757', 'f', 'C', 'I']

3909, 5955, 4, 6757, 6, 3, 9