int buttonPin = 2;
int LED = 18;
byte buttonState = LOW;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(LED, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly
  buttonState = digitalRead(buttonPin);
  if (buttonState == LOW){
    digitalWrite(LED, HIGH);
  }
  else{
    digitalWrite(LED, LOW);
  }
}