const int ledB = 8;
  const int ledR = 9;
  const int ledY = 10;
  const int ledG = 11;
  
void setup() {
  pinMode(ledB, OUTPUT);
  pinMode(ledR, OUTPUT);
  pinMode(ledY, OUTPUT);
  pinMode(ledG, OUTPUT);
}

void loop() {
  digitalWrite(ledR, HIGH);
  delay(200);
  digitalWrite(ledR, LOW);
  digitalWrite(ledY, HIGH);
  delay(200);
  digitalWrite(ledY, LOW);
  digitalWrite(ledG, HIGH);
  delay(200);
  digitalWrite(ledG, LOW);
  digitalWrite(ledB, HIGH);
  delay(200);
  digitalWrite(ledB, LOW);
}