char data ;
int buffer_size;

void setup() {
  pinMode(LED_BUILTIN,OUTPUT);
  Serial.begin(9600);
  Serial.println();
  // put your setup code here, to run once:

}

void loop() {
  buffer_size = Serial.available();

  if(buffer_size > 0){
    data = Serial.read();
    
    Serial.print(data);
    Serial.print("-");
    Serial.println(buffer_size);

    if(data == '1') {
      digitalWrite(LED_BUILTIN, HIGH);
    }
    else if (data == '0'){
      digitalWrite(LED_BUILTIN, LOW);
    }

  }

}