【HDOJ 1001】Sum Problem

import java.util.*;

public class Main {
    public static void main(String[] args){
        long sum=0,n=0;
        Scanner input = new Scanner( System.in );
        while( input.hasNextInt() ){
            sum=0;
            n = input.nextInt();
            for(int i=1;i<=n;i++)sum+=i;
            System.out.println(sum);
            System.out.println();
        }
    }
}