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: ['j', 'R', '2435']

SOLUTION: 2435

PROBLEM: ['J', 'm', '1255', 'S']

SOLUTION: 1255

PROBLEM: ['T', '4023', 's', '487', 'M', 'D']

SOLUTION:
4510

