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: ['I', 'J', 'K', 'D', '5961']

SOLUTION: 5961

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

SOLUTION: 20362

PROBLEM: ['7781', '3907']

SOLUTION:
11688