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', 'f', 'Y', '8709', '3353', 's', 'n', 'p', '3905', '5649', 'O', 'P', 'q', 'b', 'o', '2927', 'r', 'G', 'u', 'n', 'W', 'P', '9709', '1259', 'q', '9499', 'u', '5395', 'j', '6267', 'C', '1959', '9989', '1709']

6415, 6, 25, 8709, 3353, 19, 14, 16, 3905, 5649, 15, 16, 17, 2, 15, 2927, 18, 7, 21, 14, 23, 16, 9709, 1259, 17, 9499, 21, 5395, 10, 6267, 3, 1959, 9989, 1709