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: ['6415', 'H', 'L', '4337', '8187', 'n', 'k', '9537', '4917', 'Z', '4497', 'J', '473', 'K', 'h', 'u', 'P', 'K', '4255', '1557', 'r', 'A', 'c', 'J', '3769', '2681']

6415, 8, 12, 4337, 8187, 14, 11, 9537, 4917, 26, 4497, 10, 473, 11, 8, 21, 16, 11, 4255, 1557, 18, 1, 3, 10, 3769, 2681