instruction:
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:
['8739', 'K']
answer:
8739


question:
['3145', 'C', '7725', 'k', 'z']
answer:
10870


question:
['1375', 'w', 'b', 'R', 'i']
answer:

1375