다음 Java 프로그램의 실행 결과를 쓰시오.

public class Main {
    static String uniqueReverse(String value, int index) {
        if (index < 0) return "";
        char current = value.charAt(index);
        String rest = uniqueReverse(value, index - 1);
        return rest.indexOf(current) >= 0 ? rest : current + rest;
    }

    public static void main(String[] args) {
        String value = "abacad";
        System.out.print(uniqueReverse(value, value.length() - 1));
    }
}