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: ['6577', 'Q', '6865', '7671', 'N']

SOLUTION: 21113

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

SOLUTION: 24749

PROBLEM: ['5221', 'U', 'A', 'o', '407', '6831', 'c', 'b', '1069', '7513', 'M', '993']

SOLUTION:
22034