const int buttonPin = 4; // the number of the pinMode pin
const int ledPin = 5; // the number of the LED pin

//variable for storing the pushbutton status 
int buttonState = 0;

void setup()
{
  Serial.begin(115200);
  // initialize the pushbutton pin as an input
  pinMode(buttonPin, INPUT);
  // initialize the LED pin as an output
  pinMode(ledPin, OUTPUT); 
}

void loop()
{
  // read the state of the pushbutton value
  buttonState = digitalRead(buttonPin);
  Serial.println(buttonState);
  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH
  if(buttonState == HIGH)
  {
    // turn LED on
    digitalWrite(ledPin, HIGH);
  }
  else
  {
    // turn LED off
    digitalWrite(ledPin, LOW);
  }
}