void setup() {
pinMode(8, OUTPUT);  
pinMode(9, OUTPUT);
pinMode(10, INPUT_PULLUP);
pinMode(11, INPUT_PULLUP);
pinMode(12, INPUT_PULLUP);
pinMode(13, INPUT_PULLUP);
}

void loop() {
 if (digitalRead(11)==LOW) {
    digitalWrite(8,HIGH);
    digitalWrite(9,LOW);
}
else if (digitalRead(12)==LOW){
  digitalWrite (8, LOW);
  digitalWrite (9, HIGH);
}
else if (digitalRead(13)==LOW){
   digitalWrite(8,HIGH);
   digitalWrite(9,HIGH);
}
else {
   digitalWrite (9, LOW);
   delay(100);
   digitalWrite(9, HIGH);
   digitalWrite(8, HIGH);
   delay(100);
   digitalWrite(9, LOW);
   digitalWrite(8, LOW);
   delay(100);
}
}