public class IntInterval: IntSequence{

  private int from, to;

  public IntInterval(int from, int to){
    this.from = from;
    this.to = to;
  }

  public int From{
    get{return from;}
  }

  public int To{
    get{return to;}
  }

  public override int Min{
    get {return Math.Min(from,to);}
  }

  public override int Max{
    get {return Math.Max(from,to);}
  }
    
  public override int Sum(){
    int res = 0;
    int lower = Math.Min(from,to),
        upper = Math.Max(from,to);

    for (int i = lower; i <= upper; i++) 
       res += i;
    return res;
  }
}