public class Trail
{
  /** Representation of the trail. The number of markers on the trail is markers.length. */
  private int[] markers = null;
  
  public Trail(int[] theArray)
  {
    markers = theArray;
  }
  
  /** Determines if a trail segment is level. A trail segment is defined by a starting marker,
    * an ending marker, and all markers between those two markers.
    * A trail segment is level if it has a difference between the maximum elevation
    * and minimum elevation that is less than or equal to 10 meters.
    * @param start the index of the starting marker
    * @param end the index of the ending marker
    * Precondition: 0 <= start < end <= markers.length - 1
    * @return true if the difference between the maximum and minimum
    * elevation on this segment of the trail is less than or equal to 10 meters;
    * false otherwise.
    */
  public boolean isLevelTrailSegment(int start, int end)
  { 

  }
  
  /** Determines if this trail is rated difficult. A trail is rated by counting the number of changes in
    * elevation that are at least 30 meters (up or down) between two consecutive markers. A trail
    * with 3 or more such changes is rated difficult.
    * @return true if the trail is rated difficult; false otherwise.
    */
  public boolean isDifficult()
  { 
  }
  
  public static void main(String[] args)
  {
    int[] markers1 = {100,150,105,120,90, 80, 50, 75, 75, 70, 80, 90, 100};
    Trail trail = new Trail(markers1);
    boolean r1 = trail.isLevelTrailSegment(7,10);
    System.out.println("the trail between marker 7 and 10 should be level (true) and you got " + r1);
    r1 = trail.isLevelTrailSegment(2,12);
    System.out.println("the trail between marker 2 and 12 should not be level (false) and you got " + r1);
    r1 = trail.isDifficult();
    System.out.println("the trail should be difficult (true) and you got " + r1);
    int[] markers2 = {100,150,160,140,120};
    trail = new Trail(markers2);
    r1 = trail.isDifficult();
    System.out.println("the trail should be not be difficult (false) and you got " + r1);
  }

}