Codebreaker game

#include <algorithm>
#include <cstddef>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <istream>
#include <ostream>
#include <sstream>
#include <string>
#include <vector>

const std::vector<int>::size_type SIZE(5);

std::ostream & operator << (std::ostream &os, const std::vector<int> &vi)
{
    for (std::vector<int>::const_iterator ci = vi.begin(); ci != vi.end(); ++ci)
        os << *ci << ' ';

    return os;
}

std::istream & operator >> (std::istream &is, std::vector<int> &vi)
{
    while (true)
    {
        vi.clear();

        std::string ts; // Temporary String

        std::getline(std::cin, ts);

        std::stringstream tss(ts); // Temporary String Stream
        int ti; // Temporary Integer
        bool skipped(false);

        while (tss >> ti)
            if (ti < 1 || ti > 9)
            {
                std::cerr << "Only numbers between 1 and 9 are allowed!\n";
                skipped = true;
                break;
            }
            else
                vi.push_back(ti);

        if (vi.size() != SIZE)
        {
            if (!skipped)
                std::cerr << "You didn't give exactly " << SIZE << " numbers. It matters.\n";
        }
        else
            break;

        std::cerr << "Let's try this again.\n\n";
    }

    return is;
}

struct RandomOneToNine
{
    int operator () () const
    {
        return std::rand() % 9 + 1;
    }
};

std::vector<int> create_secret()
{
    RandomOneToNine rotn;
    std::vector<int> r(SIZE);

    std::generate(r.begin(), r.end(), rotn);
    return r;
}

std::string compare_similarity(const std::vector<int> &guessed, const std::vector<int> &actual)
{
    std::string r;

    for (std::vector<int>::size_type i=0; i < guessed.size(); ++i)
        if (guessed.at(i) == actual.at(i))
            r += "A ";
        else
        if (std::find(actual.begin(), actual.end(), guessed.at(i)) != actual.end())
            r += "C ";
        else
            r += "- ";

    return r;
}

int main()
{
    std::srand(std::time(NULL));

    const std::vector<int> actual(create_secret());
    std::vector<int> guessed;

    std::cout << "Please input " << SIZE << " numbers between 1 and 9, separated by space:\n";

    while (std::cin >> guessed)
    {
        std::cout << compare_similarity(guessed, actual) << '\n';

        if (guessed == actual)
        {
            std::cout << "Congratulations, you have won!" << std::endl;
            break;
        }
        else
            std::cout << "Try again!\n\n";

        std::cout.flush();
    }

    std::system("PAUSE");
}