void setup(){
	Serial.begin(9600);
	pinMode(13,OUTPUT);

	Serial.println("enter a number");
	while(Serial.available()==0);
	int num = Serial.parseInt();
	for(  ; num%2==0;  ){
		digitalWrite(13,HIGH);
		delay(500);
		digitalWrite(13,LOW);
		delay(500);

		Serial.println("enter a number");
		while(Serial.available()==0);
		num = Serial.parseInt();
	}
}
void loop(){
}