void setup() {
 pinMode (13, OUTPUT);
pinMode (12, OUTPUT);
pinMode (11, OUTPUT) ;
}

void loop() {
 digitalWrite(13,HIGH);
delay(1000);
digitalWrite(13,LOW);
delay(1000);
digitalWrite(12,HIGH);
delay(1000);
digitalWrite(12,LOW);
delay(1000);
digitalWrite(11,HIGH);
delay(1000);
digitalWrite(11,LOW);
delay(1000);
}