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.

['4949', '2459', 'n', 'f', 'n', 'v', '8421', '1519', '4859', 'c', '9923', '2829', 'K', '4937', 'W', 'R']
39896

['d', '5571', '6455', '4287', 'I', 'U', 'M', '8303', '8893']
33509

['2179', '2571', '7151', '1431', 'y', 'k', '3083']

16415