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: ['D', '5207', 'E', '119', 'g', '2991', 'G', 'g', 'u']

SOLUTION: 8317

PROBLEM: ['7215', 'd', 'q', 'k', '9301', 'P', 'x', 'C', 'g', 'e', 'o', '2769', '6993', '9769', 'v', '9007', '4131', '8627', 'q']

SOLUTION: 57812

PROBLEM: ['4745', '8667', '1057', '623', 'A', 'A', '3249', '303', 'f']

SOLUTION:
18644