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: ['r', '3537', 'T', '3611', 'k', '4983', 'h', '4317', '8727', 'E', '6471', '8465', 'f', '5429', 'T', '2169', '2171', 'P', '6941', 'D']

SOLUTION: 56821

PROBLEM: ['M', 'F', '4477', '1565', '4407', 'r', 'v', '7237', '83', '5243', 'O', 'z', 'W', '7703', 'Q', 'i', '9657', 'n']

SOLUTION: 40372

PROBLEM: ['903', '8729', '5077', 'n', 'g', '8717', '799', '7431', 'U', '401', 'c']

SOLUTION:
32057