void setup() {

pinMode (13,OUTPUT);
pinMode (12, OUTPUT);
pinMode (11,OUTPUT);

}

void loop() {

digitalWrite(13,HIGH);
digitalWrite(12, LOW);
digitalWrite(11, LOW);

delay (2000);

digitalWrite(13, LOW);
digitalWrite(12, HIGH); 
digitalWrite(11, LOW);

delay(1000);


digitalWrite(13,LOW);
digitalWrite(12, LOW);
digitalWrite(11, HIGH);

delay (2000);

digitalWrite(13, LOW);
digitalWrite(12, HIGH); 
digitalWrite(11, LOW);

delay(1000);

}