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: ['6721', '7847', 'd', 'n', 'H', 'z', '2033', 'x', 'i', '4609', '7341', '4783', '3321', 'l', '3223', 'X', 'A', '1901', '2571', 'g', '5971', '5799', 'i', 'V', 'x', '953', 'k', '3947', 'T', 'e', 'P', 'l', 'E', '7969', 't']

6721, 7847, 4, 14, 8, 26, 2033, 24, 9, 4609, 7341, 4783, 3321, 12, 3223, 24, 1, 1901, 2571, 7, 5971, 5799, 9, 22, 24, 953, 11, 3947, 20, 5, 16, 12, 5, 7969, 20