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.
['1141', 'J', '8995', '8391', 'z', 's', 'n', 'O', '3847', 'z', '2595', 'D', '9499', 'R', '1477', '369', 'J', 'r', '7607', 'w']