// C++ code
//

const int ledPin = 9;

void setup()
{
  pinMode(ledPin, OUTPUT);
}

void loop()
{
 // Gradually increase brightness
  for (int brightness = 0; brightness <= 255; brightness++) {
    analogWrite(ledPin, brightness); // Set LED brightness
    delay(5); // Small delay for a smooth transition
  }

  // Gradually decrease brightness
  for (int brightness = 255; brightness >= 0; brightness--) {
    analogWrite(ledPin, brightness); // Set LED brightness
    delay(5); // Small delay for a smooth transition
  }
}