void setup() {
  pinMode(13, INPUT_PULLUP);
  pinMode(12, INPUT_PULLUP);

  pinMode(15, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(18, OUTPUT);

}

void loop() {
  digitalWrite(15, HIGH);
  delay(500);
  digitalWrite(15, LOW);
  delay(500);
  digitalWrite(4, HIGH);
  delay(500);
  digitalWrite(4, LOW);
  delay(500);
  digitalWrite(5, HIGH);
  delay(500);
  digitalWrite(5, LOW);
  delay(500);
  digitalWrite(18, HIGH);
  delay(500);
  digitalWrite(18, LOW);
  delay(500);

}