/**
 * Created by iyasuwatts on 10/17/17.
 */
import java.util.Scanner;

public class Main 
{

    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        
        System.out.println("Enter a number: ");

        int n = input.nextInt();
        int sum=0;
        for(int i=1;i<=n;i++)
        {
            sum+=i;
        
    }
      System.out.println("The sum is : " + sum);  
    }
}