import java.util.*;
/**
 * Created by Curtis Cook on 10/17/18.
 */
public class Main {

    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        System.out.println("Please input a number.");
        int n = in.nextInt();
        int count = 0;
        
        for(int i = 1; i <= n; i++) {
            count += i;
        }
        System.out.println("The sum of numbers between 1 and " + n + " is " + count);

    }
}