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: ['507', 'P', '9697', 'u', '5057']

SOLUTION: 15261

PROBLEM: ['M', '5201', '2787', 'z', '9465', 'X', 'X', '4017', '8305', 'y', '6897', 'y', '6045', '9863', 's', 'd', '3611', 'l', 'd']

SOLUTION: 56191

PROBLEM: ['1527', '4209', 'o', '7877', 'w', '5421', '8827', '5139', 'H', '1939', '4923', '6025', '9369', '1481', '7889', 'Q', 'l']

SOLUTION:
64626