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: ['l', '2871', 'v', 'l', 'o', '9803', 'a', 'p', 'u', 'b', 'R', '4747', 'B', 's', 'R', 'B', '469', '459', 'i', 'H', 'z', '2561', 't', '3271', '1089', 'T', '8605', '4499', 'N', 'b', '2129', '4323', 'R', 'S', 'j', 'u', 'U', '7083', 'y', '7749']

12, 2871, 22, 12, 15, 9803, 1, 16, 21, 2, 18, 4747, 2, 19, 18, 2, 469, 459, 9, 8, 26, 2561, 20, 3271, 1089, 20, 8605, 4499, 14, 2, 2129, 4323, 18, 19, 10, 21, 21, 7083, 25, 7749