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: ['r', '3661', 'v', '3083', '1241', '7175', '8409', '629', 'O', 'H', 'k', '8211', '1469', 'p', '4267', 'c', '8195', 'R', 'N', 'U', '7279']

18, 3661, 22, 3083, 1241, 7175, 8409, 629, 15, 8, 11, 8211, 1469, 16, 4267, 3, 8195, 18, 14, 21, 7279