#define LED_RED1 2
#define LED_YELLOW1 3
#define LED_GREEN1 4
#define LED_RED2 5
#define LED_YELLOW2 6
#define LED_GREEN2 7

void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_RED1, OUTPUT);
  digitalWrite(LED_RED1, HIGH);
  pinMode(LED_YELLOW1, OUTPUT);
  digitalWrite(LED_YELLOW1, HIGH);
  pinMode(LED_GREEN1, OUTPUT);
  digitalWrite(LED_GREEN1, HIGH);

  pinMode(LED_RED2, OUTPUT);
  digitalWrite(LED_RED2, HIGH);
  pinMode(LED_YELLOW2, OUTPUT);
  digitalWrite(LED_YELLOW2, HIGH);
  pinMode(LED_GREEN2, OUTPUT);
  digitalWrite(LED_GREEN2, HIGH);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_RED1, HIGH);  // turn the LED on (HIGH is the voltage level)
  digitalWrite(LED_GREEN2, HIGH);
  delay(1000);   
  digitalWrite(LED_RED1, LOW);  // turn the LED on (HIGH is the voltage level)
  digitalWrite(LED_GREEN2, LOW);                   // wait for a second
  digitalWrite(LED_YELLOW1, HIGH);   // turn the LED off by making the voltage LOW
  digitalWrite(LED_YELLOW2, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(LED_RED2, HIGH);
  digitalWrite(LED_GREEN1, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(LED_RED2, LOW);  // turn the LED on (HIGH is the voltage level)
  digitalWrite(LED_GREEN1, LOW);                   // wait for a second
  digitalWrite(LED_YELLOW1, HIGH);   // turn the LED off by making the voltage LOW
  digitalWrite(LED_YELLOW2, HIGH);                    // wait for a second
}