Подскажите в чем ошибка?

/**
    * Returns the index of the first occurrence of the specified element
    * in this list, or -1 if this list does not contain the element.
    * More formally, returns the lowest index {@code i} such that
    * {@code Objects.equals(o, get(i))},
    * or -1 if there is no such index.
    *
    * @param o element to search for
    * @return the index of the first occurrence of the specified element in
    *         this list, or -1 if this list does not contain the element
    * @throws ClassCastException if the type of the specified element
    *         is incompatible with this list
    *         (optional)
    * @throws NullPointerException if the specified element is null and this
    *         list does not permit null elements
    *         (optional)
    */
   int indexOf(Object o);

public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        List<Character> alphabet = Arrays.asList(
                'а', 'б', 'в', 'г', 'д', 'е', 'ё', 'ж',
                'з', 'и', 'й', 'к', 'л', 'м', 'н', 'о',
                'п', 'р', 'с', 'т', 'у', 'ф', 'х', 'ц',
                'ч', 'ш', 'щ', 'ъ', 'ы', 'ь', 'э', 'ю', 'я');

        ArrayList<String> lines = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            String s = reader.readLine();
            lines.add(s.toLowerCase());
        }

        int[] frequency = new int[33];

        for (int i = 0; i < lines.size(); i++) {
            String currentLine = lines.get(i);
            char[] chars = currentLine.toCharArray();

            for (int j = 0; j < chars.length; j++) {
                int index = alphabet.indexOf(chars[j]);

                int count = frequency[index] + 1;
                frequency[index] = count;
            }
        }
    }
}

int count = frequency[index] + 1;
frequency[index] = count;