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: ['1305', '1673', 'w']
Example Output: 2978

Example Input: ['U', '5607', 'Q', 'j', 'I', '3745', '3031']
Example Output: 12383

Example Input: ['919', '6933', '5019', 'S', 'Y', '341', '3681', '1221', '9013', 'v', '769', 'X', 'F', 'T', 'x', '5745', '2755', '3559', 'N', 'L']
Example Output:
39955