int ledPin = 13;
void setup() {
pinMode(ledPin, OUTPUT);
}
void loop() {

// 3 quick blinks to represent “S”
digitalWrite(ledPin,HIGH);
delay(150);
digitalWrite(ledPin,LOW);
delay(100);

digitalWrite(ledPin,HIGH);
delay(150);
digitalWrite(ledPin,LOW);
delay(100);

digitalWrite(ledPin,HIGH);
delay(150);
digitalWrite(ledPin,LOW);
delay(100);

delay(100); //100 milliseconds as a break of each letter

//3 quick blinks to represent “0”
digitalWrite(ledPin,HIGH);
delay(400);
digitalWrite(ledPin,LOW);
delay(100);

digitalWrite(ledPin,HIGH);
delay(400);
digitalWrite(ledPin,LOW);
delay(100);

digitalWrite(ledPin,HIGH);
delay(400);
digitalWrite(ledPin,LOW);
delay(100);

delay(100);
// 100 milliseconds delay between each letter

//3 quick blinks to represent “S” again
digitalWrite(ledPin,HIGH);
delay(150);
digitalWrite(ledPin,LOW);
delay(100);

di=gitalWrite(ledPin,HIGH);
delay(150);
digitalWrite(ledPin,LOW);
delay(100);

digitalWrite(ledPin,HIGH);
delay(150);
digitalWrite(ledPin,LOW);
delay(100);

delay(100); // wait 100 milliseconds seconds to repeat the next S. O.S signal
}