//'main' method must be in a class 'Rextester'.
//openjdk version '11.0.5'
//Lokesh reddy 7002
import java.util.*;
import java.lang.*;

class Rextester
{  
    public static void main(String args[])
    {
        int n;
         int sum;
         Scanner in = new Scanner(System.in);
        System.out.println("Enter the number:\n");
         n=in.nextInt();
         sum=0;
            for(int i=1;i<=n;i++)
            {
               sum+=i;
            }
         System.out.println("The sum of numbers up to "+n+" is :"+sum);
    }
}