const int buttonPin = 2;
const int ledPin = 13;

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

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

  if(buttonState == LOW) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }
}