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: ['9403', 'u', '4159', 'w', '3467']

SOLUTION: 17029

PROBLEM: ['b', '5447', 'R', '8489', 'L', '627', 'P', '7491', 'c', 'c', 'r', '6923', '1167']

SOLUTION: 30144

PROBLEM: ['9647', 'F', 'Y', 'h', 'o', '731', '5457', '7839', 'c', '8115', 'U', '7595']

SOLUTION:
39384