int tala;

void setup() {
  pinMode(3, OUTPUT);              //segir að pinni 3 sé output (útgangur)
  pinMode(4, OUTPUT);              //segir að pinni 4 sé output (útgangur)
  pinMode(5, OUTPUT);              //segir að pinni 5 sé output (útgangur)
  Serial.begin(9600);
  Serial.println("Stimplaðu inn tölu 1-7");

}

void loop() {
  if(Serial.available() > 0) {
    tala = Serial.parseInt();
    if(tala == 1) {
      digitalWrite(3, HIGH);
      digitalWrite(4, LOW);
      digitalWrite(5, LOW);
    }
     if(tala == 2) {
      digitalWrite(3, LOW);
      digitalWrite(4, HIGH);
      digitalWrite(5, LOW);     
    }
    if(tala == 3) {
      digitalWrite(3, HIGH);
      digitalWrite(4, HIGH);
      digitalWrite(5, LOW);     
    }
    if(tala == 4) {
      digitalWrite(3, LOW);
      digitalWrite(4, LOW);
      digitalWrite(5, HIGH);     
    }
    if(tala == 5) {
      digitalWrite(3, HIGH);
      digitalWrite(4, LOW);
      digitalWrite(5, HIGH);     
    }
    if(tala == 6) {
      digitalWrite(3, LOW);
      digitalWrite(4, HIGH);
      digitalWrite(5, HIGH);     
    }
    if(tala == 7) {
      digitalWrite(3, HIGH);
      digitalWrite(4, HIGH);
      digitalWrite(5, HIGH);     
    }
    if(tala == 0) {
      digitalWrite(3, LOW);
      digitalWrite(4, LOW);
      digitalWrite(5, LOW);     
    }
    Serial.end();
    Serial.begin(9600);
  } 
}