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: ['5715', 'r', 'R']

SOLUTION: 5715

PROBLEM: ['c', 'E', 'M', '1303', 'y', 'H']

SOLUTION: 1303

PROBLEM: ['8953', 'Q', 'B', 'T', 'B']

SOLUTION:
8953