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: ['W', '4453', '5895', 'Z', 'A', '7663', '2749', 'f', 'H', '6917', '1215', 'M', '1775', '5397', 'l', '8197', '5209', '8229', 'U']

SOLUTION: 57699

PROBLEM: ['z', '3199', 'r', '849', 'C', 'v', '1931', 'M', 'Q', '4531', '579', 'x', '8997', '4663']

SOLUTION: 24749

PROBLEM: ['7429', '8515']

SOLUTION:
15944