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: ['6457', 'V', 'x', '605', '5771', '4303', 's', 'G', 't', 'n', '6599', 'E', '509', '207', 'L', '3757', '581', '9079', '5117', '8549', '6395', 'j', '7323', 'd', '5031', '7069', 'r', 'n', '1613', 'm', '3969', 'D', 'N', '1211', '1515', 'H', 'l']

6457, 22, 24, 605, 5771, 4303, 19, 7, 20, 14, 6599, 5, 509, 207, 12, 3757, 581, 9079, 5117, 8549, 6395, 10, 7323, 4, 5031, 7069, 18, 14, 1613, 13, 3969, 4, 14, 1211, 1515, 8, 12