void setup() {
pinMode(13, OUTPUT);
}
void loop() {
  digitalWrite(13, HIGH); 
  for (int x=0; x < 1000; x++) {
      delay(1); 
      if (x==500)
      {
        digitalWrite(12, HIGH);
      }
      }
  digitalWrite(13, LOW);
  for (int x=0; x < 1000; x++) {
    if (x==500)
    {
      digitalWrite(12, LOW);
    }
  delay(1);
  }
}