int lastMillis = -1;
int currentMillis = -1;
int buttonState = -1;
int buttonLastState = -1;
int button = 3;
int led = 4;

void setup() {
  // put your setup code here, to run once:
  pinMode(button, INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
  buttonState = digitalRead(button);
  currentMillis = millis();

  if(buttonState != buttonLastState){
    if(buttonState == LOW){
      digitalWrite(led, HIGH);
      lastMillis = millis();
    }
  }

  if(currentMillis - lastMillis > 2000){
    digitalWrite(led, LOW);
  }

}