void setup() {
  // put your setup code here, to run once:
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  for (int i = 0; i < 5; i++)
  {
    digitalWrite(i, HIGH);
    delay(500);
  }

  for (int i = 0; i < 5; i++)  
  {
    digitalWrite(i, LOW);
    delay(500);
  }
}