const int BUTTON = 2;  // Button pin
const int LED = 3;     // LED pin
int ledState = LOW;    // Start with LED OFF
int buttonState;       
int lastButtonState = HIGH;  // Because of pull-up

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP); // Use internal pull-up resistor
}

void loop() {
  buttonState = digitalRead(BUTTON);

  // Detect button press (LOW when pressed)
  if (buttonState == LOW && lastButtonState == HIGH) {
    delay(50); // debounce
    ledState = !ledState; // Toggle LED state
    digitalWrite(LED, ledState);
  }

  lastButtonState = buttonState;
}