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.
--------
Question: ['4949', '2459', 'n', 'f', 'n', 'v', '8421', '1519', '4859', 'c', '9923', '2829', 'K', '4937', 'W', 'R']

Answer: 39896


Question: ['U', 'd', '893', 'h', '9679', '315', 'H', '339', '2381', '847', '7951', 'e', '9269', '9081', 'o', '6439', 'N', '4531']

Answer: 51725


Question: ['6699', '923', 'R', 'M', 'o', 'b', 'm', 'k', '4155', '4869', '7495', '179', '1611', '793', 'U', 'N', 'M']

Answer:
26724