5

 // C++ code

//

void setup()

{

  pinMode(LED_BUILTIN, OUTPUT);

}

void loop()

{

  digitalWrite(LED_BUILTIN, HIGH);

  delay(1000); // Wait for 1000 millisecond(s)

  digitalWrite(LED_BUILTIN, LOW);

  delay(1000); // Wait for 1000 millisecond(s)

}