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: ['x', '5151', 't', '8243', '971', 'V', 'd', '45', '6787', 'P', '2319', '6725', 'x', 'r', 'u', 'g', '9921', '8853', '249', '7881', 'W', 'x']

24, 5151, 20, 8243, 971, 22, 4, 45, 6787, 16, 2319, 6725, 24, 18, 21, 7, 9921, 8853, 249, 7881, 23, 24