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: ['L', 'w', '2783', '6993', 'd', '9173']

SOLUTION: 18949

PROBLEM: ['n', '6729', 'p', 'D', 'o', '1213', 'e', '6951', '2341', '9997', 'e', 'M', 'x', 'R']

SOLUTION: 27231

PROBLEM: ['2683', '6997', '3107', '6323', '4157', '7659', 'a', 'W', 'D', 'M', 'I', 'd', '1747']

SOLUTION:
32673