const int LED = 2;
const int BTN = 4;

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(BTN, INPUT_PULLUP);
  Serial.begin(115200);
  Serial.println("Hold the button to light the LED");
}

void loop() {
  int pressed = digitalRead(BTN) == LOW;
  digitalWrite(LED, pressed ? HIGH : LOW);
  Serial.println(pressed ? "pressed" : "released");
  delay(200);
}