import java.util.Scanner;
/**
 * Created by iyasuwatts on 10/17/17.
 */
public class Main {

    public static void main(String[] args){
        Scanner reader = new Scanner(System.in);
        int sum = 0;
        int n = 0;
        boolean isANumber = false;
        
        System.out.println("Input a number:");
        while (!isANumber) {
            try {
                n = Integer.parseInt(reader.nextLine());
                isANumber = true;
            } catch (Exception e) {
                System.out.println("That's not a number");
            }
        }
        
        for (int i = 1; i <= n; i++) {
            sum += i;
        }
        System.out.println("The sum from 1 to " + n + " is: " + sum);
    }
}