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: ['U', '5607', 'Q', 'j', 'I', '3745', '3031']
Example Output: 12383

Example Input: ['2013', 'S', 's', '9353', 'b', 'u', '6687', '5429', '3545', '7269']
Example Output: 34296

Example Input: ['4315', '2503', '3575']
Example Output:
10393