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.
['5223', '4193', '8897', '7907', 'N', '2389', 's', '8405', '3767', '8243', 'n', 'h', 'N', '4213', 'p', '4549', '2093', '711']