int index = 0;
    String rev = "";

    for(int i = s.length()-1;i>=0;i--){
        rev+=s.charAt(i);
    }

    String x = rev;

    for(int i = 0;i<x.length();i++){

        for(int j = 0; j<chars.length();j++){
            if(x.charAt(i)==chars.charAt(j)){
                index = i;
            }else {
                index = -1;
            }
        }
    }
    System.out.println(index);
    return index;
}
    /*I KNOW WHY THIS CODE doesn't work, just tell me how I can get a code for what I asked in the question. PLease try to keep it simple with no arrays because I am in a introductory java college course.*/