void setup() { 

  pinMode(13,OUTPUT);
  pinMode(12,OUTPUT);
  pinMode(11,OUTPUT);
  pinMode(10,OUTPUT);

  // put your setup code here, to run once:

}

void loop() {

  digitalWrite(13, HIGH);
  delay(500);
  digitalWrite(13, LOW);
  delay(500);

  digitalWrite(12, HIGH);
  delay(500);
  digitalWrite(12, LOW);
  delay(500);

  digitalWrite(11, HIGH);
  delay(500);
  digitalWrite(11, LOW);
  delay(500);

  digitalWrite(10, HIGH);
  delay(500);
  digitalWrite(10, LOW);
  delay(500);
  
  // put your main code here, to run repeatedly:

}