using System;

public class Program

{

    public static void Main()

    {

        int suma, n, x;

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

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

        suma = 0; 

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

        {

            suma = suma + x;

        }

        System.Console.WriteLine("la suma es: " + suma);

        System.Console.ReadLine();

    }

}