void setup() {
  // put your setup code here, to run once:
pinMode(5, OUTPUT);
pinMode(10, OUTPUT);
pinMode(15, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(0, HIGH);
delay(100);
digitalWrite(0, LOW);
delay(200);
digitalWrite(0, HIGH);
delay(100);
digitalWrite(0, LOW);
delay(200);
digitalWrite(1, HIGH);
delay(100);
digitalWrite(1, LOW);
delay(200);
digitalWrite(1, HIGH);
delay(100);
digitalWrite(1, LOW);
delay(200);
digitalWrite(2, HIGH);
delay(100);
digitalWrite(2, LOW);
delay(200);
digitalWrite(2, HIGH);
delay(100);
digitalWrite(2, LOW);
delay(200);
digitalWrite(3, HIGH);
delay(100);
digitalWrite(3, LOW);
delay(200);
}