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: ['l', '5369', 'z', 'U', 's', '2357', '3367', 't', '6539', 'K', 'a', 'Q', 'x', 'e', '6459', 'K', 'B', 'f', 'j']

SOLUTION: 24091

PROBLEM: ['D', 'C', '7295', 'g', 'j', '1387', 'O', '4701', 'B', 'd', 'W', 'b', 's', 'n', 'n', '4917', '2941', '1825', 'x']

SOLUTION: 23066

PROBLEM: ['8397', 'H', 'k', '441', '2017', '5121', 'h', 'F', 's', 'T', 'H', 'i', '2747', '2625', 'f', 't', 'F', '8369']

SOLUTION:
29717