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]: ['Q', '9787', '7533', '9489', 'C', '1753', '5121', '1405', '9267', '4815', 's', '5887']
[EX A]: 55057

[EX Q]: ['n', 'm', 'Y', 'v']
[EX A]: 0

[EX Q]: ['8755', 'l', 'i', 'Y', 'v', 'm', 'r', 'U', 'k', '4037']
[EX A]:
12792