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: ['3507', '2205', 'J', 'I', 'D', '2473', '7773', 'a', '4949', '131', 'l', '5041', '971', 'A']

3507, 2205, 10, 9, 4, 2473, 7773, 1, 4949, 131, 12, 5041, 971, 1