int led[] = {2,3,4,5,6,7,8,9};
int ledCount;
void setup() {
  // put your setup code here, to run once:
  ledCount = sizeof(led);
  for (int i=0;i<ledCount;i++){
    pinMode(led[i], OUTPUT);
    digitalWrite(led[i], LOW);
  }
}

void loop() {
  for (int i=0;i<ledCount;i++){
    digitalWrite(led[i], HIGH);
    delay(200);
  }
  for (int i=0;i<ledCount;i++){
    digitalWrite(led[i], LOW);
  }
  delay(500);
}