// LED Pins
int red1 = 2;
int red2 = 3;
int yellow1 = 4;
int yellow2 = 5;
int green1 = 6;
int green2 = 7;

void setup() {
  // Set all pins as OUTPUT
  pinMode(red1, OUTPUT);
  pinMode(red2, OUTPUT);
  pinMode(yellow1, OUTPUT);
  pinMode(yellow2, OUTPUT);
  pinMode(green1, OUTPUT);
  pinMode(green2, OUTPUT);
}

void loop() {
  // Turn all LEDs ON
  digitalWrite(red1, HIGH);
  digitalWrite(red2, HIGH);
  digitalWrite(yellow1, LOW);
  digitalWrite(yellow2, LOW);
  digitalWrite(green1, LOW);
  digitalWrite(green2, LOW);
  delay(500); // 1 second

  // Turn all LEDs OFF
  digitalWrite(red1, LOW);
  digitalWrite(red2, LOW);
  digitalWrite(yellow1, LOW);
  digitalWrite(yellow2, LOW);
  digitalWrite(green1, LOW);
  digitalWrite(green2, LOW);
  delay(500); // 1 second
  digitalWrite(red1, LOW);
  digitalWrite(red2, LOW);
  digitalWrite(yellow1, HIGH);
  digitalWrite(yellow2, HIGH);
  digitalWrite(green1, LOW);
  digitalWrite(green2, LOW);
  delay(500); // 1 second
  digitalWrite(red1, LOW);
  digitalWrite(red2, LOW);
  digitalWrite(yellow1, LOW);
  digitalWrite(yellow2, LOW);
  digitalWrite(green1, LOW);
  digitalWrite(green2, LOW);
  delay(500); // 1 second
digitalWrite(red1, LOW);
  digitalWrite(red2, LOW);
  digitalWrite(yellow1, LOW);
  digitalWrite(yellow2, LOW);
  digitalWrite(green1, HIGH);
  digitalWrite(green2, HIGH);
  delay(500); // 1 second
  digitalWrite(red1, LOW);
  digitalWrite(red2, LOW);
  digitalWrite(yellow1, LOW);
  digitalWrite(yellow2, LOW);
  digitalWrite(green1, LOW);
  digitalWrite(green2, LOW);
  delay(500); // 1 second
}