int LED_PIN = 6;
int BUTTON_PIN = 13;

boolean buttonState;
boolean lastButtonState = LOW;
boolean ledState = LOW;

unsigned long debounceDuration = 50; // millis
unsigned long lastTimeButtonStateChanged = 0;

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT);
}

void loop() {
  if (millis() - lastTimeButtonStateChanged > debounceDuration) {
     buttonState = digitalRead(BUTTON_PIN);
    if (buttonState != lastButtonState) {
      lastTimeButtonStateChanged = millis();
      lastButtonState = buttonState;
      if (buttonState == LOW) {
        ledState = !ledState;
        digitalWrite(LED_PIN, ledState);
      }
    }
  }
}