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]: ['3839', 'D', '4741', 'L']
[EX A]: 8580

[EX Q]: ['Q', '1669']
[EX A]: 1669

[EX Q]: ['k', '8669', 'D']
[EX A]:
8669