// Define pin numbers
const int buttonPin = 20; // D0
const int ledPin = 8;    // D8

void setup() {
  // Initialize the button pin as an input
  pinMode(buttonPin, INPUT);

  // Initialize the LED pin as an output
  pinMode(ledPin, OUTPUT);

  // Turn off the LED initially
  digitalWrite(ledPin, LOW);
}

void loop() {
  // Read the state of the button
  int buttonState = digitalRead(buttonPin);

  // If the button is pressed, turn on the LED
  if (buttonState == HIGH) {
    digitalWrite(ledPin, HIGH);
  } else {
    // Otherwise, turn off the LED
    digitalWrite(ledPin, LOW);
  }
}