void setup() {
  // put your setup code here, to run once:
  for(int i=0; i<11;i++){

    pinMode(i, OUTPUT);
  }

}

void loop() {
  // put your main code here, to run repeatedly:
  for (int j=0;j<11; j++){
  digitalWrite(j, HIGH);
  delay(500);
  }

for (int j=11;j>=0; j--){
  digitalWrite(j, LOW);
  delay(500);
}

}