const int arr[] = {5,6,9,22};

void setup() {
  // put your setup code here, to run once:
  for(int i=0;i<4;i++)
  pinMode(arr[i], OUTPUT);
}

void loop()
 {
  // put your main code here, to run repeatedly:
  for(int i=0;i<4;i++)
  {
     digitalWrite(arr[i], HIGH);
     delay(1000);
     digitalWrite(arr[i], LOW);
     
  }
  delay(1000);
  for(int i=4;i>0;i--)
  {
     digitalWrite(arr[i], HIGH);
     delay(1000);
     digitalWrite(arr[i], LOW);
     
  }
  delay(1000);
 // this speeds up the simulation
}