import java.util.*;
/** Inactive Edge List for Scan Line Algorithm*/

class IEL extends EdgeList{
  int miny = Integer.MAX_VALUE;
  int maxy = Integer.MIN_VALUE;

  /* add edge at appropriate place in IEL */
  void add (Edge e) {
    miny = Math.min(e.miny(),miny);
    maxy = Math.max(e.maxy(),maxy);
    //v is in decreasing order of ymin()
    int i;
    for (i = 0; i < size() && e.miny() < elementAt(i).miny(); i++) {
      /*nothing*/
    }
    v.insertElementAt(e,i);
  }

  /* next edge with miny() = y from IEL */
  Edge next(int y) {
    if (size()==0) return null;
    Edge result = elementAt(size()-1); 
    if (result.miny()==y) {
      v.removeElementAt(size()-1);
      return result;
    } else {
      return null;
    }
  }

  int miny() {
    return miny;
  }

  int maxy() {
    return maxy;
  }

  /* string representation of IEL */
  public String toString(){
    StringBuffer sb = new StringBuffer();
    for (int i = size()-1; i >= 0; i--) {
      sb.append(elementAt(i));
      sb.append("\n");
    }
    return sb.toString();
  }
}