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.

[EX Q]: ['3557', '3345', '307', '9791', '1897', 'O']
[EX A]: 18897

[EX Q]: ['6469', '3027', 'Z', '3353', 'a', 'S', '3879', '8471', 'H', 'I', 'y', '2661', '9007', 'D']
[EX A]: 36867

[EX Q]: ['C', '5775', 'N', 'N', '7601', 'f']
[EX A]:
13376