2_VSHE

#include <cstdio>
#include <algorithm>
#include <vector>

template<class F, class S, class T>class triple
{
public:

    F first;
    S second;
    T third;

    triple() = default;
    ~triple() = default;

    triple(const F& f, const S& s, const T& t) : first(f), second(s), third(t) {}

    triple& operator=(const triple<F, S, T>& p)
    {
        first = p.first;
        second = p.second;
        third = p.third;
        return *this;
    }
};

int main()
{
    int n = 0;
    std::scanf("%d", &n);

    std::vector<triple<int, int, int>> time(n);

    for (int i = 0; i < n; i++)
    {
        time[i].first = i;
        std::scanf("%d%d", &time[i].second, &time[i].third);
    }

    std::sort(time.begin(), time.end(), [](
        const triple<int, int, int>& f,
        const triple<int, int, int>& s
        ) { return f.second < s.second; }
    );

    int cur_day = time.front().second;

    std::vector<std::pair<int, int>> ans(n);

    for (const auto& [ind, start, finish ] : time)
    {
        ans[ind] = cur_day > finish ? std::make_pair(-1, -1) : std::make_pair(std::max(start, cur_day), finish);
        cur_day = cur_day == finish ? cur_day + 1 : std::max(cur_day, finish);
    }

    std::for_each(
        ans.begin(),
        ans.end(),
        [](const std::pair<int, int>& p) { std::printf("%d %d\n", p.first, p.second); }
    );

    return 0;
}