int bubl = 11;
int btn = 12;
int ntb = 6;

void setup() {
  pinMode(bubl, OUTPUT);
  pinMode(btn, INPUT);
  pinMode(ntb, INPUT);
}

void loop() {
  if(digitalRead(btn)!=digitalRead(ntb) ){
    digitalWrite(bubl, HIGH);

  }
  else if(digitalRead(btn)==digitalRead(ntb)){
    digitalWrite(bubl, LOW);
  }
}