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: ['238', 'h', '92', 'U', '2799']
Example solution: 3129
Example explanation: Here, the numbers in the input list are '238', '92' and '2799', hence their sum (238+92+2799) is 3129.

Problem: ['6523', '8059', '9273', 'C', 'm', '8503', 'H', '1207', 'E', '4449', 'A', '7389', 'D']

Solution: 45403