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: ['f', 'H', 'U', 'l', 'n', 'q', '2701', '339', 'X', 'H', 'O', 'q', '2313']
Example Output: 5353

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: ['8921', 'O', '6333']
Example Output:
15254