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: ['291', 'R', 'N', '983', '2879', 'C', '3797', '4837', '793', '5489', 'k', '535', 'L', '3605', 's', '3701', 'U', '4399', '2489', '4739']

SOLUTION: 38537

PROBLEM: ['8609', '8045', '2517', '3821', 'x', '3895', 't']

SOLUTION: 26887

PROBLEM: ['4071', '4295', '1917', '1291', 'k', '3389', 'T', '45', '6701', 's', 'X', '5579', 'X', '3591', '3127', 'M', 'd', '3679', 'Z']

SOLUTION:
37685