`瑟莉姆的宴会 <https://codeforces.com/gym/105176/problem/D>`_
=================================================================

    思路很简单，先按下标顺序连成一个链，若正序不满足那倒序必定满足。
    
    最后输出即可。

    .. code-block:: cpp

        #include <bits/stdc++.h>
        #define all(a) a.begin(), a.end()
        #define int long long
        #define PII pair<int, int>
        using ll = long long;
        const int N = 1e5 + 10, INF = 1e18, MOD = 1e9 + 7;
        using namespace std;

        void solve()
        {
            int n, m;
            cin >> n >> m;

            map<PII, int> p;

            while (m--)
            {
                int u, v;
                cin >> u >> v;
                if (u < v)
                    p[{u, v}]++;
                else
                    p[{v, u}]--;
            }

            int sum = 0ll;

            for (auto [key, val] : p)
                sum += val;

            for (int i = 0; i < n; i++)
                cout << (sum >= 0 ? i : (i == n - 1 ? 0 : i + 2)) << " ";
        }
        signed main()
        {
            ios::sync_with_stdio(0), cin.tie(0);
            int T = 1;
            // cin >> T, cin.get();
            while (T--)
                solve();
            return 0;
        }