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.
['5345', 'a', '5713', '6775', 'c', '6537', 'C', '5751', '4197', '7049', '4331', 'q', 's', '8281', '4783', 'c', '9445', '3017', 'Y', '5177']