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: ['W', 'c', 'P', '425', '4133', 's', '1831', '883', '2531', '681', 'U', 'B', 'H', '237', '4245']

SOLUTION: 14966

PROBLEM: ['2585', '3043', 'w', '7697', '53', 't', 'A']

SOLUTION: 13378

PROBLEM: ['R', '3603']

SOLUTION:
3603