const int LED1 = 11;
const int LED2 = 12;
const int LED3 = 13;
void setup () {
  pinMode (LED1, OUTPUT);
  pinMode (LED2, OUTPUT);
  pinMode (LED3, OUTPUT);
}
void loop () {
  digitalWrite (LED1, LOW);
  delay (100);
  digitalWrite (LED2, HIGH);
  delay (200);
  digitalWrite(LED2, LOW);
  delay (100);
  digitalWrite (LED3, HIGH);
  delay (200);
  digitalWrite (LED3, LOW);
  delay (100);
  digitalWrite (LED1, HIGH);
  delay (200);
}