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: ['j', 'R', '2435']
Example Output: 2435

Example Input: ['z', '447', '9781', 'R', '6083', 'u', '9229', 'Z', 'F', '2437', '9677', 'n', 'G', '6763', '5883', 'B', '9563', '4575']
Example Output: 64438

Example Input: ['1407', 'f', '4869', '6791', '4105', '7729', '2761', '1151', 'y']
Example Output:
28813