#define GREEN_LED 1 
#define YELLOW_LED 2
#define RED_LED 3
#define BUTTON 5

void setup() {
  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);  
  pinMode(RED_LED, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP);
}

void loop() {
  state1();
  state2();  
  state3();
}

void state1(){
  digitalWrite(RED_LED, LOW);  
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(GREEN_LED, HIGH);  

  delay(1000);
}

void state2(){
  digitalWrite(GREEN_LED, LOW);    
  digitalWrite(YELLOW_LED, HIGH);

  if(digitalRead(BUTTON) == LOW){
    while(digitalRead(BUTTON) == LOW){
      digitalWrite(YELLOW_LED, !digitalRead(YELLOW_LED));  
      delay(500);
    }
  }

  delay(500);
}

void state3(){
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(RED_LED, HIGH);

  delay(1000);
}