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: ['L', 'G', '3981', 'p', 'U', '7947', 'V', '7131', '5603', '305', 'H']

12, 7, 3981, 16, 21, 7947, 22, 7131, 5603, 305, 8