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: ['457', '173', '6807', 'o', '555', 'l', 's', 'Z', 'm', '3035', '1283', '5645', 'S', '8641', 'J', 'Z', 'z', 'K']

Answer: 26596


Question: ['s', 'Q', 'f', 'r', 'h', '521', 'D']

Answer:
521