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', 'i', '1469', 'r', '2993', '3671', 'R', '8187', 'i', 'Z', '8727', 'A', 'M', 'F', '4329', '2401', '5129', 'T', '1481', 'l', 'l', 'o', '8909', '7001', '3799', 'S']

18, 9, 1469, 18, 2993, 3671, 18, 8187, 9, 26, 8727, 1, 13, 6, 4329, 2401, 5129, 20, 1481, 12, 12, 15, 8909, 7001, 3799, 19