TASK DEFINITION: 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.
PROBLEM: ['4607', 'T', 'a', '6077', 'c', '4761']

SOLUTION: 15445

PROBLEM: ['4145', 't']

SOLUTION: 4145

PROBLEM: ['u', '8433', 'U', '7657', 'm', '6669', 'H', '3639', '4939', '1813', '9881', '3957', 'm', 's', '6935', 'N']

SOLUTION:
53923