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: ['2417', '6671']

SOLUTION: 9088

PROBLEM: ['303', 'Q', 'Z', '6429']

SOLUTION:
6732