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: ['4271', 'N', 'M', '5239', '7037', 'x', 'U', 's', '7107', '4163', 'f', '3607', '6155']

SOLUTION: 37579

PROBLEM: ['T', '721', '6555', 'g', 'y', 'U', '3053', 'A', '9663']

SOLUTION: 19992

PROBLEM: ['6601', '8237', 'v', '1669', '4899', '1939', 'c', 'c', '8587', '3113', 'S', '3403', '3239', 'u', '4215', '8457', '1503', 'k', 'o']

SOLUTION:
55862