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: ['M', '1589', '8353', 'X', 'P', '3173', 'V', '1335', 'm', 'l', '6421', '4823', 'r', '8941', '4255', '9107', 'z', '2449', '2321', 'l']
Example Output: 52767

Example Input: ['u', 'W', '1561', '9243', '4923', '9385']
Example Output: 25112

Example Input: ['p', 'q', 'e', '6479', '8467', 'u', 'N']
Example Output:
14946