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: ['3873', 'D', 'J', '2799', 'k', 'F', 'I', '3457', '5647', '4815', '7509', 'Y', '1251', '2211']

SOLUTION: 31562

PROBLEM: ['3683', 'U', 'x', '313', 'n', '3837', '3299', '2081', '2773', 'r', 'O', '257', '6647', '585', 'o']

SOLUTION: 23475

PROBLEM: ['2545', 'I', '3315', '2771', '1713', '3587', '8239', 'B', '7047', 'Y', '4599', '171', '1371', 'h', '2977']

SOLUTION:
38335