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.
['o', 'D', 'G', '9703', '6353', 'h', 't', 'g', 'O', 'U', 'C', '9557', 'h', 'G', 'T', 'S', 'H', 's']