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]: ['X', 'f', 'p', 'R', 'N']
[EX A]: 0

[EX Q]: ['u', 'B', '2509', 'U', 'R', '7497', '1897', '8697', 't', 'W', '1021', '7937', 'F', 'g', '6901', 'I', '2957']
[EX A]: 39416

[EX Q]: ['s', 'o', 'R', 'r', 'p', '4545', '6355', '7437']
[EX A]:
18337