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.
['v', 'Y', '4135', '8645', '263', '5377', '8677', 'Z', 'W', 'g', 'n', 'r', 's', '8513', '5677', 'u', '3033', 'I']