int const  led1=4;
int const  led2=6;
int const  led3=9;
int const  led4=22;
void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
}

void loop() {
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, LOW);
  digitalWrite(led4, HIGH);
  delay(3000);
  digitalWrite(led1, HIGH);
  digitalWrite(led2, LOW);
  digitalWrite(led3, HIGH);
  digitalWrite(led4, LOW);

  delay(5000); // this speeds up the simulation
}