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.
--------
Question: ['B', 'K', '9399', 't', '5541', 'w', '1939', '7841', 'q']

Answer: 24720


Question: ['I', 'J', 'K', 'D', '5961']

Answer: 5961


Question: ['n', 'r', '8269', '4247', 'K']

Answer:
12516