void setup() {
  // put your setup code here, to run once:
  for(int led=2;led<=9;led++){
    pinMode(led, OUTPUT);
    digitalWrite(led,LOW);
  }
  pinMode(A15,OUTPUT);
  digitalWrite(A15,LOW);
  //digitalWrite(4,LOW);
}
int led[8] = {};
void loop() {
  // put your main code here, to run repeatedly:
  for(int led=2;led<=8;led+=2){
    digitalWrite(led+1,LOW);
    digitalWrite(led,HIGH);
  }
  delay(500);
  for(int led=3;led<=9;led+=2){
    digitalWrite(led-1,LOW);
    digitalWrite(led,HIGH);
  }
  delay(500);
}