#define LED 2

void setup() {
  pinMode(2, OUTPUT);  

  
  pinMode(5, OUTPUT);
  pinMode(18, OUTPUT);
  pinMode(19, OUTPUT);
  pinMode(21, OUTPUT);

  digitalWrite(5,  LOW);
  digitalWrite(18, LOW);
  digitalWrite(19, LOW);
  digitalWrite(21, LOW);

}


int periodo=25;


void loop() {
  
  digitalWrite(2, !digitalRead(2));
  

  digitalWrite(5,  HIGH);
  digitalWrite(18, LOW);
  digitalWrite(19, LOW);
  digitalWrite(21, LOW);
  delay(periodo);
  
  digitalWrite(5,  LOW);
  digitalWrite(18, HIGH);
  digitalWrite(19, LOW);
  digitalWrite(21, LOW);
  delay(periodo);

  digitalWrite(5,  LOW);
  digitalWrite(18, LOW);
  digitalWrite(19, HIGH);
  digitalWrite(21, LOW);
  delay(periodo);

  digitalWrite(5,  LOW);
  digitalWrite(18, LOW);
  digitalWrite(19, LOW);
  digitalWrite(21, HIGH);
  delay(periodo);



}