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.

Example Input: ['D', '5207', 'E', '119', 'g', '2991', 'G', 'g', 'u']
Example Output: 8317

Example Input: ['I', '7815']
Example Output: 7815

Example Input: ['W', 'w', 'j', 'w', 'a', 'c', '1815', '4259', 'r', '9315', 'f']
Example Output:
15389