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

// variables for storing the pushbutton status and LED state
int buttonState = 0;
int lastButtonState = 0;
int ledState = LOW;

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);

  // check for a button press (transition from HIGH to LOW)
  if (buttonState == HIGH && lastButtonState == LOW) {
    // toggle the LED state
    ledState = (ledState == LOW) ? HIGH : LOW;
    // update the LED
    digitalWrite(ledPin, ledState);

    // print the LED state to the Serial monitor
    Serial.println(ledState);
  }

  // save the current button state for the next iteration
  lastButtonState = buttonState;
}