void setup() {
  pinMode(5, OUTPUT);
  pinMode(18, OUTPUT);
  pinMode(19, OUTPUT);  
}

void loop() {
  if(digitalRead(15) == HIGH){
    digitalWrite(5, HIGH);
    digitalWrite(18, LOW);
    digitalWrite(19, LOW);
    delay(1000);
  
    digitalWrite(5, LOW);
    digitalWrite(18, HIGH);
    digitalWrite(19, LOW);
    delay(1000);
    
    digitalWrite(5, LOW);
    digitalWrite(18, LOW);
    digitalWrite(19, HIGH);
    delay(1000);
  }
  else{
    digitalWrite(5, LOW);
    digitalWrite(18, LOW);
    digitalWrite(19, LOW);
  }
}