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: ['3609', 'S', '6199', 'p', 'a', '4855', 'S', '7811', '9995', 'f', '5945', '4649', 'j', 'f', '3445', 'U', '957', 's', '723', '8669', '1257', 't', 'F']

3609, 19, 6199, 16, 1, 4855, 19, 7811, 9995, 6, 5945, 4649, 10, 6, 3445, 21, 957, 19, 723, 8669, 1257, 20, 6