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: ['R', 'C', 'S', 'x', '1529', 'r']

SOLUTION: 1529

PROBLEM: ['I', '7815']

SOLUTION: 7815

PROBLEM: ['2077', '5589', '8847', 'V', '2717', 'P', 'X', 'X', '3371', '4707', '1595', 'z']

SOLUTION:
28903