const int rojo=12;
const int amarillo=14;
const int verde=27;

void setup(){
  pinMode(rojo, OUTPUT);
  pinMode(amarillo, OUTPUT);
  pinMode(verde, OUTPUT);
}

void loop(){
digitalWrite(rojo, HIGH);
delay(2000);
digitalWrite(rojo, LOW);
delay(1000);

digitalWrite(amarillo, HIGH);
delay(2000);
digitalWrite(amarillo, LOW);
delay(1000);

digitalWrite(verde, HIGH);
delay(2000);
digitalWrite(verde, LOW);
delay(1000);

digitalWrite(amarillo, HIGH);
delay(2000);
digitalWrite(amarillo, LOW);
delay(1000);
}