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: ['4975', 'M', 'C', 'D', 't', 'i', 't', 'L']
Example Output: 4975

Example Input: ['7459', '491', '7823', '6965', 'H', '109', 'R', 't', '3959', '2821', 'R', '2807', 'o', 'v', '1305', 'a', '1411', 'r', '3669']
Example Output: 38819

Example Input: ['3013', 'T', 'U', 'o', 'Y', '3449', '4465']
Example Output:
10927