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: ['D', 'G', '9895', '143', '37', 'S', '1539', 'x', 'a', 'x', 'B', 'i', '9719', '839']

SOLUTION: 22172

PROBLEM: ['3331', '5791', 'r', 'Q', '2243', '8229']

SOLUTION: 19594

PROBLEM: ['g', 'U', 'A', 'f', '2391', 's', 'G', 'E', 'a', '7345', '6949', 't', '3357', 'n', '851', 'P']

SOLUTION:
20893