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: ['c', '4501', 'O']
Example Output: 4501

Example Input: ['s', '9377', '3663', '1375', 'j', 'L', '7943', '1711', '7409', '9115', '1227', 'I', 'U']
Example Output: 41820

Example Input: ['6387', '3315', 'n', '4481', 'G', 'K', 'q', 'I', 'x', 'Z', 'a', '5839']
Example Output:
20022