int wait = 200;

void setup() {
  for(int i=4; i <14; i++){
    pinMode(i, OUTPUT);
  }
  // put your setup code here, to run once:


}

void loop() {
  for(int i=4;i<14; i++){
    digitalWrite(i, HIGH);
    delay(wait);
  }
  for(int i=14;i>=4; i--){
    digitalWrite(i,LOW);
    delay(wait);
  }

  // put your main code here, to run repeatedly:

}