void setup() {
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, INPUT);
  pinMode(10, INPUT);
}

void loop() {
  digitalWrite(12, LOW);    // set the LED off
  digitalWrite(13, LOW);    // set the LED off
  int t = random(1,9);
  delay(t*1500);
  digitalWrite(12, HIGH);   // set the LED on

  int s1 = 0;
  int s2 = 0;
  while (!s1 && !s2) {
  s1=digitalRead(11);  //
  s2=digitalRead(10);  //
  }

  if(s1 && !s2) {
    digitalWrite(13, HIGH);   // set the LED on
    digitalWrite(12, LOW);   // set the LED off
  }
  else if(!s1 && s2) {
    digitalWrite(13, LOW);   // set the LED off
    digitalWrite(12, HIGH);   // set the LED on
  }else {
    digitalWrite(13, HIGH);   // set the LED on
    digitalWrite(12, HIGH);   // set the LED on
  }
  delay(2000);              // wait for a second
}