#define BUTTON_PIN 13
#define RELAY_PIN  16

bool lightState = false;
int lastButtonState = LOW;
unsigned long lastDebounceTime = 0;

void setup() {
  pinMode(BUTTON_PIN, INPUT);
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW);
}

void loop() {
  int reading = digitalRead(BUTTON_PIN);

  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > 100) {
    if (reading == HIGH) {
      lightState = !lightState;
      digitalWrite(RELAY_PIN, !lightState);
    }
  }
  
  lastButtonState = reading;
}