class Value 
{
  private int val;
  private bool isValid = false;

  public  Value(int v) 
  { 
    isValid = true; 
    val = v; 
  }
  public Value() {
    // Called for nonvalid value. Basically empty... But lets be proper:
    isValid = false;
  }

  public bool IsSet() 
  { 
    return set; 
  }
}