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: ['4083', '6881', 'U', '4157', 'M', '6791', 'U', '453', 'i', '5113', '7371', 'H', '3191', '319', '3027', '5207', '9979', 'd', '133', 'm', '6453', '9279', '8377', '3099', '1735', 'R', '173', '3775', 'W', 'n', 'r', 'J', '1865', '8519', 'e', 'L']

4083, 6881, 21, 4157, 13, 6791, 21, 453, 9, 5113, 7371, 8, 3191, 319, 3027, 5207, 9979, 4, 133, 13, 6453, 9279, 8377, 3099, 1735, 18, 173, 3775, 23, 14, 18, 10, 1865, 8519, 5, 12