#define PIN_LED_RED   0   //define the red led pin
#define PIN_LED_YELLOW   2   //define the yellow led pin
#define PIN_LED_GREEN  15   //define the green led pin

void setup() {
  pinMode(PIN_LED_RED, OUTPUT);
  pinMode(PIN_LED_YELLOW, OUTPUT);
  pinMode(PIN_LED_GREEN, OUTPUT);
}

void loop() {
   digitalWrite(PIN_LED_GREEN, HIGH);// turns on the green led
   delay(5000);// delays 5 seconds
   digitalWrite(PIN_LED_GREEN, LOW); // turns off the green led
   for(int i=0;i<3;i++)// flashes 3 times.
{
   delay(500);// delays 0.5 second
   digitalWrite(PIN_LED_YELLOW, HIGH);// turns on the yellow led
   delay(500);// delays 0.5 second
   digitalWrite(PIN_LED_YELLOW, LOW);// turns off the yellow led
} 
   delay(500);// delays 0.5 second
   digitalWrite(PIN_LED_RED, HIGH);// turns on the red led
   delay(5000);// delays 5 second
   digitalWrite(PIN_LED_RED, LOW);// turns off the red led
}