import java.awt.Graphics;

public class c07_lsystems extends java.applet.Applet {
  static final int left = 30;
  static final int h = 300;

  double x, y;
  double dx, dy;
  java.util.Stack stack = new java.util.Stack();

  class State {
    double x, y, dx, dy;

    State()
    {
      this.x = c07_lsystems.this.x;
      this.y = c07_lsystems.this.y;
      this.dx = c07_lsystems.this.dx;
      this.dy = c07_lsystems.this.dy;
    }

    void restore()
    {
      c07_lsystems.this.x = this.x;
      c07_lsystems.this.y = this.y;
      c07_lsystems.this.dx = this.dx;
      c07_lsystems.this.dy = this.dy;
    }
  }

  public void paint(Graphics g)
  {
    for (int stage = 7; stage <= 7; stage++) {
      x = left+h/2;
      y = left+h;
      dx = 0;
      dy = -10*(stage+1);
      forward(g, stage);
    }
  }

  void forward(Graphics g, int stage)
  {
    if (stage > 0) {
      forward(g, stage-1);
      save();
      left();
      forward(g, stage-1);
      restore();
      save();
      right();
      forward(g, stage-1);
      restore();
    } else {
      g.drawLine((int)x, (int)y, (int)(x+dx), (int)(y+dy));
      x += dx;
      y += dy;
    }
  }

  void left()
  {
    double dx1 = dx;
    dx = 0.707 * dx1 - 0.707 * dy;
    dy = 0.707 * dx1 + 0.707 * dy;
  }

  void right()
  {
    double dx1 = dx;
    dx = 0.866 * dx1 + 0.500 * dy;
    dy = -0.500 * dx1 + 0.866 * dy;
  }

  void save()
  {
    stack.push(new State());
    dx *= 0.7;
    dy *= 0.7;
  }

  void restore()
  {
    State state = (State)stack.pop();
    state.restore();
  }
}