const int button = 4;
const int led = 2;

int ledState = LOW;
int buttonState = HIGH;
int lastButtonState = HIGH;

unsigned long lastDebounceTime = 0;
long debounceDelay = 50;

void setup() {
  pinMode(button, INPUT_PULLUP);
  pinMode(led, OUTPUT);
  digitalWrite(led, ledState);
}

void loop() {
  int reading = digitalRead(button);
  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) {
        ledState = !ledState;
        digitalWrite(led, ledState);
      }
    }
  }
  
  lastButtonState = reading;
}