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.
--------
Question: ['291', 'R', 'N', '983', '2879', 'C', '3797', '4837', '793', '5489', 'k', '535', 'L', '3605', 's', '3701', 'U', '4399', '2489', '4739']

Answer: 38537


Question: ['29', 'N', '5061', '7191', 'z', '8367']

Answer: 20648


Question: ['4773', 'S', 'z', '5383', '5079', '4161', '5771', '3867', '6111']

Answer:
35145