using System;

public class Program

{

    public static void Main()

    {

        //Ochoa Luna Carlos Damiann 3A TPR

        //P0224

        int N,suma,x;

        suma=0;

        System.Console.WriteLine("Dame N numeros a suma");

        N=int.Parse(System.Console.ReadLine());

        for(x=1;x<=N; x++)

        {

            suma=suma+x;

        }

        Console.Write("suma "+suma);

    }

}