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: ['i', 'C', '5373', '2017', 'm', '5435', 'Y', 'h']
Example Output: 12825

Example Input: ['v', 't', 'a', 'r', 'O', 'I']
Example Output: 0

Example Input: ['g', '6139', '2535', '9107', 'n', 'U', 'q', 'I', 'p', '485', '2849', 'z']
Example Output:
21115