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.
['p', 'T', 'B', '7443', '3439', '6789', 'h', '3931', 's', 'h', '863', 'I', 'x', 'r', 'b', '5057', '5969', '7353', 'y']