class Countdown
{
  private int countStart, currCount, timer;
  boolean running;
  
  Countdown(int c)
  {
    countStart = c;
  }
  
  void start()
  {
    currCount = countStart;
    timer = millis();
    running = true;
  }
  
  void update()
  {
    if ( millis() - timer > 1000 ) 
    {
      currCount--;
      timer = millis();
    }
    fill(255, 0, 0);
    textSize(80);
    textAlign(CENTER);
    if ( currCount > 0 ) 
    {
      text(currCount, width/2, height/2);
    }
    else
    {
      text("GO!", width/2, height/2);
    }      
    textAlign(LEFT);
    textSize(24);
    if ( currCount < 0 ) running = false;
  }
}