#include <vector>
#include <algorithm>

class permutations {
public:
    class iterator {
    public:
        iterator(const std::vector<int> &data, bool isDone) : m_data{data}, m_isDone{isDone} {}

        iterator &operator++()
        {
            m_isDone = std::next_permutation(m_data.begin(), m_data.end());

            return *this;
        }

        const std::vector<int> &operator*() const
        {
            return m_data;
        }

        bool operator==(const iterator &other) const { return m_isDone == other.m_isDone; }
        bool operator!=(const iterator &other) const { return m_isDone != other.m_isDone; }

    private:
        std::vector<int> m_data = {};
        bool m_isDone = false;
    };

    permutations(const std::vector<int> &data) : m_data{data}
    {
        std::sort(m_data.begin(), m_data.end());
    }

    iterator begin() const { return iterator(m_data, false); }
    iterator end() const { return iterator({}, true); }

private:
    std::vector<int> m_data = {};
};