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: ['B', '4831', 'b', 't', 'P', 'l', '4863', 'C', 'r', 'r']

2, 4831, 2, 20, 16, 12, 4863, 3, 18, 18