void setup() {
  // put your setup code here, to run once:
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
pinMode(10, OUTPUT);
pinMode(11, OUTPUT);
pinMode(12, OUTPUT);
pinMode(13, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(8, HIGH);
delay(500);
digitalWrite(8, LOW);
delay(500);
digitalWrite(9, HIGH);
delay(500);
digitalWrite(9, LOW);
delay(500);
digitalWrite(10, HIGH);
delay(500);
digitalWrite(10, LOW);
delay(500);
digitalWrite(11, HIGH);
delay(500);
digitalWrite(11, LOW);
delay(500);
digitalWrite(12, HIGH);
delay(500);
digitalWrite(12, LOW);
delay(500);
digitalWrite(13, HIGH);
delay(500);
digitalWrite(13, LOW);
delay(500);
digitalWrite(12, HIGH);
delay(500);
digitalWrite(12, LOW);
delay(500);
digitalWrite(11, HIGH);
delay(500);
digitalWrite(11, LOW);
delay(500);
digitalWrite(10, HIGH);
delay(500);
digitalWrite(10, LOW);
delay(500);
digitalWrite(9, HIGH);
delay(500);
digitalWrite(9, LOW);
delay(500);
digitalWrite(8, HIGH);
delay(500);
digitalWrite(8, LOW);
delay(500);
digitalWrite(9, HIGH);
delay(500);
digitalWrite(9, LOW);
delay(500);
digitalWrite(10, HIGH);
delay(500);
digitalWrite(10, LOW);
delay(500);
digitalWrite(11, HIGH);
delay(500);
digitalWrite(11, LOW);
delay(500);
digitalWrite(12, HIGH);
delay(500);
digitalWrite(12, LOW);
delay(500);
digitalWrite(13, HIGH);
delay(500);
digitalWrite(13, LOW);
delay(500);
digitalWrite(12, HIGH);
delay(500);
digitalWrite(12, LOW);
delay(500);
digitalWrite(11, HIGH);
delay(500);
digitalWrite(11, LOW);
delay(500);
digitalWrite(10, HIGH);
delay(500);
digitalWrite(10, LOW);
delay(500);
digitalWrite(9, HIGH);
delay(500);
digitalWrite(9, LOW);
delay(500);
digitalWrite(8, HIGH);
delay(500);
digitalWrite(8, LOW);
delay(500);
}