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: ['5715', 'r', 'R']

Answer: 5715


Question: ['d', '4553']

Answer: 4553


Question: ['9087', '8481', 'u', 'n', '5991', '8001', '6149', 'K', '3157', 'o', 'k', '9853', 'm', '2269']

Answer:
52988