import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class Teljed4 extends Applet implements ActionListener{
  double a=3;
  TextField tf1=new TextField(String.valueOf(a));
  double b=5;
  TextField tf2=new TextField(String.valueOf(b));
  double c=5;
  TextField tf3=new TextField(String.valueOf(c));
  double d=5;
  TextField tf4=new TextField(String.valueOf(d));
  double vanay;
  public Teljed4(){
    add(tf1);
    add(tf2);
    add(tf3);
    add(tf4);
    tf1.addActionListener(this);
    tf2.addActionListener(this);
    tf3.addActionListener(this);
    tf4.addActionListener(this);
  }
  public void paint(Graphics g){
    g.drawLine(100, 0, 100, getHeight());
    g.drawLine(  0, 200, getWidth(), 200);
    int algx=-100;
    vanay=a*algx*algx*algx+b*algx*algx+c*algx+d;
    for(int x=algx; x<100; x++){
      double y=a*x*x*x+b*x*x+c*x+d;
      if(y*vanay<=0){
         g.drawOval((int)x+100-5, 200-5, 10, 10);  
      }
      g.drawOval(x+100, 200-(int)y, 1, 1);
      vanay=y;
    }
//    double nullkoht=-b/a;
//    g.drawOval((int)nullkoht+100-5, 200-5, 10, 10);
  }
  public void actionPerformed(ActionEvent e){
     a=Double.parseDouble(tf1.getText());
     b=Double.parseDouble(tf2.getText());
     c=Double.parseDouble(tf3.getText());
     d=Double.parseDouble(tf4.getText());
     repaint();
  }


  public static void main(String argumendid[]){
    Frame f=new Frame("Ruutfunktsiooni graafik");
    f.add(new Teljed4());
    f.setSize(250, 250);
    f.setVisible(true);
  }
}