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(250);
}
  for(int x=11; x>=0; x--){
    digitalWrite(x, LOW );
    delay(250);
}
}