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.

Example Input: ['W', 'c', '7971', 'J', 'o']
Example Output: 7971

Example Input: ['C', '9973', 'b', '693', 'y', 'H', 'C', 'P', 'b', 'J', 'f', 'T', '2317', 'O', '5755', '8201', 'p', 'y', '8721', 'i']
Example Output: 35660

Example Input: ['e', '3563', '2311']
Example Output:
5874