1 2
0001 0009
#include <iostream>
#include <stdio.h>
using namespace std;
int main()
{
long long int n;
while (cin >> n)
{
long long int result;
result = ((n * (n+1) / 2) %10000) * ((n * (n+1) /2) %10000) %10000;
printf("%04lld\n",result);
}
return 0;
}原文：http://blog.csdn.net/xiaotan1314/article/details/46415153