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]: ['4869', 'L']
[EX A]: 4869

[EX Q]: ['k', 'a']
[EX A]: 0

[EX Q]: ['1309', 'W', '2731', 'f', 'I', '4663']
[EX A]:
8703