public static int count_letter(int x)
    {
        if(x < 10)
        {
            return one_digit[x];
        }

        if(x < 100)
        {
            if(x % 10 == 0)
            {
                return two_10[x/10];
            }
            if(x < 20)
            {
                return teen[x - 10];
            }

            return two_10[x / 10] + one_digit[x % 10];
        }

        if(x < 1000)
        {
            if(x % 100 == 0)
            {
                return one_digit[x/100] + hundred;
            }

            return one_digit[x/100] + hundred + _and + count_letter(x % 100);
        }

        if(x == 1000)
        {
            return one_digit[1] + thousand;
        }

        return -1;
    }