// define led according to pin diagram in article
const int led1 = 1;     // GREEN
const int led2 = 2;     // GREEN
const int led3 = 3;    // YELLOW
const int led4 = 4;    // GREEN
const int button1 = 0;  // Button

void setup() {

  Serial.begin(9600); //copy from examples

  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(button1, INPUT);
}

void loop() {
  int buttonState = digitalRead(button1);
  
  Serial.println(buttonState);

  digitalWrite(led1, HIGH);  // turn the LEDs on
  delay(200);
  digitalWrite(led2, HIGH);
  delay(200);
  digitalWrite(led3, HIGH);
  delay(200);
  digitalWrite(led4, HIGH);

  if (digitalRead(button1) == HIGH) {
    digitalWrite(led4, HIGH);
    delay(400); // if button
  } else {
    digitalWrite(led4, LOW);
    delay(100);
    digitalWrite(led4, HIGH);
  }

  // off
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);

  delay(500);  // wait for a second
}