const int buttonPin = 4;  
const int ledPin =  5;    
int buttonState = 0;
void setup() {
  Serial.begin(115200);  
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);
}
void loop()
 {
  buttonState = digitalRead(buttonPin);
  Serial.println(buttonState);
  if (buttonState == HIGH) 
  {
    digitalWrite(ledPin, HIGH);
  } else 
  {
    digitalWrite(ledPin, LOW);
  }
}