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: ['3855', 'F', 'S', '6481', '8821', '1853', '3815', '4585', 'u', '8599', 'I', '4017', '5323', 'o', 'k', 'u', 'P', 'P', 'U', '379']

3855, 6, 19, 6481, 8821, 1853, 3815, 4585, 21, 8599, 9, 4017, 5323, 15, 11, 21, 16, 16, 21, 379