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.
['3433', 'S', 'c', 't', '9347', '3441', 'y', '8697', '4419', '5949', 'h', 'a', 'c', 'Y', 'O', '8263', '3447', 'Q']