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.
['c', 'S', '3603', '8069', 'E', '865', 'd', '4263', '1577', 'O', '4395', 'a', '1795', '1945', '8393', '7045', '3293', '3711']