const int ledPin = 9;
const int buttonPin = 5;

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

unsigned long lastDebounceTime = 0;
unsigned long debounceDelay = 50; 

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);
  
  // start with led off
  digitalWrite(ledPin, ledState);
}

void loop() {
  int reading = digitalRead(buttonPin);

  if (reading != lastButtonState) {
    lastDebounceTime = millis();  
    lastButtonState = reading;
  }

  if (millis() - lastDebounceTime > debounceDelay) {
    if (reading != buttonState) {
      buttonState = reading;

      if (buttonState == LOW) {
        ledState = !ledState;
      }
    }
  }
  digitalWrite(ledPin, ledState);
 
}