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: ['7121', 'R', 'j', '7337', 'm', 'V', 'H', '4863', 'L', '5909', 'x', '2517', '9263', '6043', '4539', 'K']

7121, 18, 10, 7337, 13, 22, 8, 4863, 12, 5909, 24, 2517, 9263, 6043, 4539, 11