OJ-Problems-Source/HDOJ/1001_autoAC.cpp

#include <iostream>
using namespace std;
int main()
{
    int n,sum;
    while(cin>>n)
    {
        sum = 0;
        for(int i = 1;i <= n;++i)
            sum += i;
        cout<<sum<<endl<<endl;
    }
    return 0;
}