void setup() {
 pinMode(13, OUTPUT);
 pinMode(12, OUTPUT);
 pinMode(11, OUTPUT);

}

void loop() {
  digitalWrite(13, HIGH);
  delay(150);
  digitalWrite(13, LOW);
  delay(50);
  Serial.print("S");
  digitalWrite(12, HIGH);
  delay(600);
  digitalWrite(12, LOW);
  delay(50);
  Serial.print("O");
  digitalWrite(11, HIGH);
  delay(150);
  digitalWrite(11, LOW);
  delay(50);
  Serial.print("S");
}