int led[5] = {
  4, 5, 6, 7
};
void setup() {
  // put your setup code here, to run once:
  for (int i = 0; i < 4; i++) {
    pinMode(led[i], OUTPUT);
  }
  digitalWrite(led[1], LOW);
  pinMode(4, OUTPUT);
}
void loop() {
  // put your main code here, to run repeatedly:
  for (int i = 0; i < 5; i++) {
    digitalWrite(led[i], HIGH);
    delay(500);
  }
  for (int i = 5; i > 0; i--) {
    digitalWrite(led[i], LOW);
    delay(500);
  }
  digitalWrite(4, LOW);
  delay(500);
}