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: ['1709', 'S', 'w', '7725', 'Z', '7755', '8081', '897', 'N', '4449', 'F', 'F', 'M', 'y', 'B', 'h', 's', 'l', 's', '415']

SOLUTION: 31031

PROBLEM: ['A', '9775', '5867', 'n', '1329', '5973']

SOLUTION: 22944

PROBLEM: ['1351', 'f', '9795', '6651']

SOLUTION:
17797