const int ledPin = 10;      // LED connected to pin 9
const int buttonFadeIn = 2; // Fade-in button
const int buttonFadeOut = 3; // Fade-out button

int brightness = 0;        // Initial brightness
int fadeAmount = 50;       // Amount to fade

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(buttonFadeIn, INPUT);
  pinMode(buttonFadeOut, INPUT);
}

void loop() {
  if (digitalRead(buttonFadeIn) == HIGH) {
    // Fade in
    brightness += fadeAmount;
    if (brightness > 255) {
      brightness = 255; // Limit to max brightness
    }
    analogWrite(ledPin, brightness);
    delay(50); // Adjust for speed of fade
  }

  if (digitalRead(buttonFadeOut) == HIGH) {
    // Fade out
    brightness -= fadeAmount;
    if (brightness < 0) {
      brightness = 0; // Limit to min brightness
    }
    analogWrite(ledPin, brightness);
    delay(50); // Adjust for speed of fade
  }
}