public class Sumup
{

  public static int sumup(int n)
  {
    int sum = 0;
    for (int i = 1; i <= n; i++)
    {
      sum = sum + i;
    }
    return sum;
  }


  public static int sumup2(int n)
  {
    int sum;
    if (n == 0)
      sum = 0;
    else
      sum = sumup2(n-1) + n;
    return sum;
  }


  public static void main(String args[])
  {
    int k = Integer.parseInt(args[0]);
    int answer = sumup2(k);
    System.out.println("The sum is " + answer);
  }
}