using System;

public class Program

{

    public static void Main()

    {

        //Sanchez Rojas Maria Fernanda

        //3A TPR

        int suma,n,i;

        Console.WriteLine("Introduce hasta que numero deseas sumar: ");

        n=System.Convert.ToInt32(Console.ReadLine());

        suma=0;

        for (i=1; i<=n; i++)

        {

            suma=suma+i;

        }

        Console.WriteLine("La suma es: "+ suma);

    }

}