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: ['139', '401', '7291', '6557', '4363', 'I', 'k', '1613', '4285', 'C', 'R', '1365']

139, 401, 7291, 6557, 4363, 9, 11, 1613, 4285, 3, 18, 1365