const int buttonPin =4;
  const int ledPin = 16;

  int buttonState=0; 

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

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