import java.awt.*;

class Array extends Panel
{
  private int size;             // so many number buttons
  private Font plain, bold;     // fonts for the number buttons

  public Array(int sizeOf)
  {
    super();
    size = sizeOf;
    plain = new Font("Dialog", Font.PLAIN, 12);
    bold = new Font("Dialog", Font.BOLD, 12);

    // the number buttons are in a grid
    setLayout(new GridLayout(0, 10));
    // make the number buttons
    for (int i = 1; i <= size; i++) {
      Button b = new Button(String.valueOf(i));
      b.setFont(bold);
      add(b);
    }
    // "1" is not a prime, pre-disable it
    getComponent(0).disable();
    getComponent(0).setFont(plain);
  }

  public boolean action(Event evt, Object what)
  {
    // get button label, supposedly a number
    int b;
    try {
      b = Integer.parseInt((String)what);
    } catch (NumberFormatException e) {
      return super.action(evt, what);
    }
    // sift
    Component c;
    for (int i = b+b; i <= size; i += b) {
      c = getComponent(i-1);
      if (c.isEnabled()) {
        c.disable();
        c.setFont(plain);
      }
    }
    return true;
  }
}

public class Sieve extends java.applet.Applet
{
  private static final int defaultSize = 50;
  private int size = defaultSize;
  private Array array;          // the number buttons
  private TextField sizeEntry;  // user enters desired size here
  private Button commit;        // start/re-start button

  public void init()
  {
    array = new Array(defaultSize);
    sizeEntry = new TextField( String.valueOf(defaultSize), 4 );
    commit = new Button("Reset");

    Panel top = new Panel();    // use this to contain sizeEntry and commit
    top.add(new Label("Size:", Label.RIGHT));
    top.add(sizeEntry);
    top.add(commit);

    add(top);
    add(array);
  }

  public boolean action(Event e, Object arg)
  {
    if (e.target == commit) {   // user pushes the button
      commit.disable();
      // get user's new size
      int newSize;
      try {
        newSize = Integer.parseInt(sizeEntry.getText());
      } catch (NumberFormatException ex) {
        return false;           // in case user enters non-number, nevermind
      }
      // further check of newSize, like, it should be >= 2
      if (newSize < 2)
        return false;           // if not >= 2, nevermind
      remove(array);
      size = newSize;
      array = new Array(size);
      add(array);               // assume it has been the last guy
      validate();
      commit.enable();
      return true;
    }
    return super.action(e, arg);
  }
}