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: ['1551', 'p', 'C', 'u', '9819', 'l', '7213', 'k', '8445', 'o', 'A', '609', '3259', 'I', 'P', 'Q', 'e', '7101', '8803', '3241', 't', '9283', 'n', '3029', 'a', '847', 'e', 'I', 'U', '6115', '6655', 'M']

1551, 16, 3, 21, 9819, 12, 7213, 11, 8445, 15, 1, 609, 3259, 9, 16, 17, 5, 7101, 8803, 3241, 20, 9283, 14, 3029, 1, 847, 5, 9, 21, 6115, 6655, 13