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.

['2787', 'z', '9351', '3339']
15477

['4749', '1169', '4273', 'X']
10191

['U', 'P', '1381', 'C', 'u', '3725', '3167', 'r', 'b', 'q', 'v', '8797', 'c', 'R', '9839', 'c', 'H', 'm']

26909