In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.

Ex Input:
['r', 'B', '8791', '3165', 'n', 'm']

Ex Output:
11956

Ex Input:
['8821', '7221']

Ex Output:
16042

Ex Input:
['8439', '1143']

Ex Output:
9582