TASK DEFINITION: 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.
PROBLEM: ['4949', '2459', 'n', 'f', 'n', 'v', '8421', '1519', '4859', 'c', '9923', '2829', 'K', '4937', 'W', 'R']

SOLUTION: 39896

PROBLEM: ['6367', '9923', '9141']

SOLUTION: 25431

PROBLEM: ['s', '9135', '1899', 'q', '6473', '3335', 't', '7949', 'm', 'b', 'y', 'Q']

SOLUTION:
28791