*/
    public static void main(String[] args) {
        StringBuilder a=new StringBuilder("0000");
        int i=a.length()-1;
        StringBuilder b=binHesapla(a,i);
    }

    private static StringBuilder binHesapla(StringBuilder binn,int i) {
        StringBuilder bin=new StringBuilder(binn);
         if(bin.indexOf("0")==-1){
             System.out.println(bin);
             return bin;
         }
        int gezen=Character.getNumericValue(bin.charAt(i));
        if(++gezen==2){
            bin.setCharAt(gezen, '0');
            bin.setCharAt(gezen-1, '1');
            System.out.println(bin);
            return binHesapla(bin,i-1);
        }
        bin.setCharAt(gezen, '1');
        return binHesapla(bin,i-1);