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: ['O', 'z', '5199', '3719', '2257', 'U', 'z', 't', '5023', 'H', 'h', '6149', 'v', 'b', 'n', 'w', '6763', 'M', '8415', 'Y', 'L', 'P', 'M', '4163', 'f', 's', 'u', '1617', '1811', 'I', '6381', 'r']

15, 26, 5199, 3719, 2257, 21, 26, 20, 5023, 8, 8, 6149, 22, 2, 14, 23, 6763, 13, 8415, 25, 12, 16, 13, 4163, 6, 19, 21, 1617, 1811, 9, 6381, 18