* @param args
     */
    public static void main(String[] args) {
        System.out.println(increment("1239"));

    }

    public static String increment(String s) {
        StringBuffer p = new StringBuffer(s);



        if (p.charAt(p.length() - 1) != 9) {
            int k = p.charAt(p.length() - 1);
            p.setCharAt(p.length() - 1, (char) (k + 1));
        } else {
            int i = 0;
            while (p.charAt(p.length() - 1 - i) == '9') {
                p.setCharAt(p.length() - 1 - i, '0');
                i = i + 1;

            }
            if ( i+1!=p.length()) {
                int k = p.charAt(p.length() - 1 - i);
                p.setCharAt(p.length() - 1 - i, (char) (k + 1));
            } else {
                p.setCharAt(p.length() - i - 1, '0');
                p.insert(0, '1');

            }

        }

        return p.toString();
    }

}