public class IntToBinary {
  // !!!!! DER REST DER AUFGABE IST IN DER README.md BEANTWORTED !!!!!
  
  public int binary(int n) {
    if (n < 0) {
      // Invalid input
      return -1;
    } else if (n <= 1) {
      return n;
    } else {
      // Prevent adding the numbers by converting to String and convert it back to int after
      return Integer.parseInt(Integer.toString(binary(n/2)) + (n%2)); 
    }
  }
}