void setup() {
  for (int i = 2 ; i <= 7; i++) {
    pinMode(i, OUTPUT);
  }
}
void loop() {
  for (int i = 2 ; i <= 7; i++) {
    digitalWrite(i, HIGH);
  }
  delay(500);
  for (int i = 2 ; i <= 7; i++) {
    digitalWrite(i, LOW);
    delay(100);
  }
  delay(100);
  for (int i = 7 ; i >= 2; i--) {
    digitalWrite(i, HIGH);
    delay(100);
  }
}