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: ['9739', 'u', '963', 'R', '7281', 'B', 'E', '165', 'e', 'L', '7851']

9739, 21, 963, 18, 7281, 2, 5, 165, 5, 12, 7851