const int pin1 = 13; 

void setup() {
  Serial.begin(9600);
 
  pinMode(pin1, OUTPUT); 
}

void loop() {
  String rcvString = "";
 
 while ( Serial.available() )
 
 {    // While there is data in the buffer
 
   char c = (char)Serial.read();

    //Serial.println(c);
 
   rcvString += c;     
      
 delay(3);
    
 }

if ( rcvString.length() >0 ) {
    //Serial.println( rcvString );
 
   Serial.flush();

    if( rcvString == "0") {
      digitalWrite(pin1, HIGH);
      delay(100);
      //Serial.println("Light On");
    }
    else if( rcvString == "1") {
      digitalWrite(pin1, LOW);
      delay(100);
      //Serial.println("Light Off");
    }

}}