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: ['t', 'v', 'C', 'U', 'I', '5851', 'S', 't', 'z', '6599', 'N', 't', 'k', 'd', 'V', 'B', '5333', '5863', '6239']

20, 22, 3, 21, 9, 5851, 19, 20, 26, 6599, 14, 20, 11, 4, 22, 2, 5333, 5863, 6239