## Problem Description

Give you a signed integer n (n<=10000), please tell me the sum of its all non-negative factors, and all its factors must larger than zero. Say, give you 12, you know, 1,2,3,4,6 are its factors.
So the answer would be 1+2+3+4+6=16.
if n < 0 , just output "0"

There are several test cases, for evey case, there is exactly one line containing an integer N (N<=10000).

## Sample Input

1
2
3
4

## Sample Output

0
1
1
3

## Source

FZU 2009 Summer Training IV--Number Theory