const int ledPin = 9;
const int buttonPin = 2;
int buttonState = 0;
int lastButtonState = 0;
int brightnessMode = 0;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  digitalWrite(ledPin, LOW);
}

void loop() {
  buttonState = digitalRead(buttonPin);
  if (buttonState != lastButtonState) {
    delay(50);
    if (buttonState == LOW) {
      brightnessMode++;
      if (brightnessMode == 1) {
        analogWrite(ledPin, 50);
      }
      else if (brightnessMode == 2) {
        analogWrite(ledPin, 100);
      }
      else if (brightnessMode == 3) {
        analogWrite(ledPin, 255);
      }
      else if (brightnessMode == 4) {
        digitalWrite(ledPin, LOW);
        brightnessMode = 0;
      }
    }
  }
  lastButtonState = buttonState;
}