int button = 2;
int LED = 4;

int buttonState;
unsigned long debounceDuration = 100; //Wait to validate second change in button state
unsigned int lastTimeButtonStateChanged; //Check last time state was changed
byte lastButtonState;

void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
  pinMode(button, INPUT);

  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  //Debouncing
  if (millis()-lastTimeButtonStateChanged > debounceDuration) {
    buttonState = digitalRead(button);
    if (buttonState != lastButtonState) {
      lastTimeButtonStateChanged = millis();
      lastButtonState = buttonState;
    }

  }

  if (buttonState == 1) {
    digitalWrite(LED, HIGH);
  }

  else {
    digitalWrite(LED, LOW);
  }

  Serial.println(buttonState);
  delay(500);
}