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: ['2915', '4443', 'Z', '3409', '1417', 'H', 'T', 'u', '3373', 'U', '115', 'R']

SOLUTION: 15672

PROBLEM: ['6669', 'n', 't', 'N', 'x', '8153', 'W', 'v', 'B', '3181', 'y', 'e', '3491']

SOLUTION: 21494

PROBLEM: ['c', '3519', 'g', '427', 'l', 'g', 'X', 'B', 'd', 'K', '4093', '2011', '5447']

SOLUTION:
15497