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.

Ex Input:
['4975', 'M', 'C', 'D', 't', 'i', 't', 'L']

Ex Output:
4975


Ex Input:
['t', 'v', 'B', 'Y']

Ex Output:
0


Ex Input:
['1971', '4307', 'R']

Ex Output:

6278