void setup() {
  
  pinMode(3, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
}

void loop() {
  
  digitalWrite(2, HIGH);
  delay(200);
  digitalWrite(3, HIGH);
  delay(200);
  digitalWrite(6, HIGH);
  delay(200);
  digitalWrite(7, HIGH);
  delay(200);
  digitalWrite(2, LOW);
  delay(200);
  digitalWrite(3, LOW);
  delay(200);
  digitalWrite(6, LOW);
  delay(200);
  digitalWrite(7, LOW);
}