Тест №9 не проходит.

//2138. Хороший, плохой, злой
public class olimpSumDif {
    StreamTokenizer in;
    //StringTokenizer inString;
    PrintWriter     out;
        public static void main(String[] args) throws IOException
        {
            new olimpSumDif().run();
        }

        int nextInt() throws IOException
        {
            in.nextToken();
            return (int)in.nval;
        }

        String nextString() throws IOException
        {
        in.nextToken();
        return (String) in.sval;
        }

        void run() throws IOException
        {
            in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
            //inString = new StringTokenizer (new BufferedReader(new InputStreamReader(System.in)));
            out = new PrintWriter(System.out);
            solve();
            out.flush();
        }

        void solve() throws IOException
        {
            String b = nextString();
            int a = nextInt();
            out.print(integerToSingleDigitAndReverse(a));
        }
        long integerToSingleDigitAndReverse(long number) {
            int digit = (int) number;
            ArrayList<Long> array = new ArrayList();
            for (int i = 0; i < 4; i++)
                array.add((long)Math.floor(digit/Math.pow(256,i) % 256));
            Collections.reverse(array);
            number = 0;
            for (int i = 0; i < 4; i++)
                number = number +  array.get(i)*((long)Math.pow(256, i)) ;
            return number;
        }

}

Отбой, решил. В граничном случае использовал int, нужен long.