const int buttonPin = 4;  // the number of the pushbutton pin
const int ledPin =  5;    // the number of the LED pin
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() 
{
    buttonState = digitalRead(buttonPin);

  if (buttonState == HIGH) 
  {
    // turn LED on
    digitalWrite(ledPin, HIGH);
  } else 
  {
    // turn LED off
    digitalWrite(ledPin, LOW);
  }
}