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.
['Y', 'M', '5469', '5995', '1473', '3121', 'y', '1081', 'W', 'A', 'o', '4119', 'C', 'c', 'i', 'a', '9495', 'U', '5329', '13']