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: ['u', 's', '2939', 't', 'R', '8153', '2831', 'Z', 'C', 'H', '6323', 'u', '431', 'N', '7025', '55', '3987', 'F', 'K', 'V', 'T', 'Y', '8915', 'v', '4945', '3675', 'Y', 'C', '395', '2123', '1439', 'E']

21, 19, 2939, 20, 18, 8153, 2831, 26, 3, 8, 6323, 21, 431, 14, 7025, 55, 3987, 6, 11, 22, 20, 25, 8915, 22, 4945, 3675, 25, 3, 395, 2123, 1439, 5