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: ['q', '5151', 'R', '441']

SOLUTION: 5592

PROBLEM: ['1391', '1719', '8547', 'x', 'a', 'j', '6395', 't', '3421', '6607', 'M', '1645', 'H', 'x', 't']

SOLUTION: 29725

PROBLEM: ['k', '9937', 'j', 'Y']

SOLUTION:
9937