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: ['1891', 'A', 'E', '2131', '7811', '9253', 'S', 'p', '641']

1891, 1, 5, 2131, 7811, 9253, 19, 16, 641