int incomingByte = 0;	// for incoming serial data

void setup()
{
Serial.begin(9600);
pinMode(3,OUTPUT);

}

void loop(){
  digitalWrite(3,HIGH);
  
  ///// Get Number from processing
  if (Serial.available() > 0) {
	incomingByte = Serial.read();    // read the incoming byte:
	Serial.println(incomingByte);    // say what you got:

     if( incomingByte == 5 ){
           digitalWrite(3,LOW);
           delay(100);
            digitalWrite(3,HIGH);
            }
      }

}