void setup() {
  // Setup the digital pin 0-10 as OUTPUT pins using a for loop
  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 x=10; x>=0; x-- )
 {
  digitalWrite(x, LOW);
  delay(500);
 }
}