void setup() {
  pinMode(13,output);
  pinMode(12,output);
  pinMode(11,output);
}

void loop() {
  digitalWrite(13, HIGH);
  delay(1000);
   digitalWrite(13, LOW);
  delay(500);
  digitalWrite(12, HIGH);
  delay(1000);
   digitalWrite(12, LOW);
  delay(500);
  digitalWrite(11, HIGH);
  delay(1000);
   digitalWrite(11, LOW);
  delay(500);
   
}