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: ['1867', '5301', 'x', '3867', '8707', '2429', 'K', '59', '6629', 'v', 'A', 'y', 'P', '3829', '1979', 'R', '8481', '5767', 'h', 'U']

SOLUTION: 48915

PROBLEM: ['R', '9751', '4367', 'l', 'N', '5125', '8751', '7507', 'y', 'K', '6127']

SOLUTION: 41628

PROBLEM: ['3521', '3', 'O', 'V', 'F', 'F']

SOLUTION:
3524