#include<iostream>

#include<stdio.h>

using namespace std;

int main()

{

    long long n;

    while(~scanf("%I64d",&n))

    {

        printf("%I64d\n\n",((+n)*n)>>);

    }

    return ;

}

import java.io.*;

import java.math.BigInteger;

import java.util.*;

public class hdu1000 {

    public static void main(String[] args) {

        // TODO Auto-generated method stub

         Scanner cin=new Scanner (new BufferedInputStream(System.in));

            PrintWriter cout=new PrintWriter(System.out);

            while(cin.hasNextBigInteger())

            {

                BigInteger t=cin.nextBigInteger();

                BigInteger m=cin.nextBigInteger();

                BigInteger ans =0;

                ans=t.add(m);

                System.out.println(ans);

            }

    }

}