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: ['K', '479', 'u', '3489', 'o', '9589', '7153', '7649', '123', 'a', 'A', '3951', '847', 'N', 'R', '947', '9243', 'G', 'a']
Example Output: 43470

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

Example Input: ['t', '1521', 'r', 'W', 'N', 'N', '8557', '9233', '2271', 'Y', 'u', '757', '347', 'S']
Example Output:
22686