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: ['s', '3607', 'p', 'P', '9285', 'J', 'l', '9863', '9823', '2817', 'g', '9751', '599', '2605', 'k', 'Y', 'O', 'U', '9649']

SOLUTION: 57999

PROBLEM: ['7959', '1345', '4605', '6453', 'Q']

SOLUTION: 20362

PROBLEM: ['1973', '4471', 'K']

SOLUTION:
6444