void setup() {
  // put your setup code here, to run once:
   for(int led=8; led<=11; led++){
    pinMode(led, OUTPUT);
   }

}

void loop() {
  // put your main code here, to run repeatedly:
  for(int led=8; led<=11; led++){
    digitalWrite(led, HIGH);
    delay(500);
    digitalWrite(led, LOW);
    delay(500);
   }
 
}