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: ['S', '1249', '6233', 'I', '6733', 'r', 'A', 'E', 'h', 'x', 'p', 'c', '515', '1029', '1593', '1035']
Example Output: 18387

Example Input: ['4975', 'M', 'C', 'D', 't', 'i', 't', 'L']
Example Output: 4975

Example Input: ['h', '6937', 'U', 'f', 'S', 'm', '9699', 'E', '4559', 'p', 'Z', 'o', '6409', 's', '4537', '5135', '6901', '6489', '5833', 'l']
Example Output:
56499