func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     cout.precision(30);     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int n;     cin >> n;     vector<pair<long long, long long>> ps(n);     for (int i = 0; i < n; i++) {       cin >> ps[i].first >> ps[i].second;     }     sort(ps.begin(), ps.end(),          [&](pair<long long, long long> a, pair<long long, long long> b) {            return make_pair(a.second, a.first) < make_pair(b.second, b.first);          });     vector<long long> hadv(n, 0), hadh(n, 0);     vector<pair<long long, long long>> v, h;     vector<pair<pair<long long, long long>, pair<long long, long long>>> verts;     long long cury = ps[0].second;     for (int i = 1; i < n; i++) {       if (cury != ps[i].second) {         cury = ps[i].second;       } else {         hadv[i - 1] = 1;         hadv[i] = 1;         verts.push_back({ps[i - 1], ps[i]});       }     }     for (int i = 0; i < n; i++) {       if (!hadv[i]) v.push_back(ps[i]), v.push_back(ps[i]);     }     sort(ps.begin(), ps.end());     vector<pair<pair<long long, long long>, pair<long long, long long>>> hors;     long long curx = ps[0].first;     for (int i = 1; i < n; i++) {       if (curx != ps[i].first) {         curx = ps[i].first;       } else {         hadh[i - 1] = 1;         hadh[i] = 1;         hors.push_back({ps[i - 1], ps[i]});       }     }     for (int i = 0; i < n; i++) {       if (!hadh[i]) h.push_back(ps[i]), h.push_back(ps[i]);     }     swap(hors, verts);     swap(h, v);     auto inter = [&](pair<long long, long long> a, pair<long long, long long> b,                      pair<long long, long long> c, pair<long long, long long> d) {       if (c.first < a.first && a.first < d.first) {         if (a.second < c.second && c.second < b.second) return true;       }       return false;     };     vector<vector<long long>> g(verts.size());     for (int i = 0; i < verts.size(); i++) {       for (int j = 0; j < hors.size(); j++) {         if (inter(verts[i].first, verts[i].second, hors[j].first, hors[j].second))           g[i].push_back(j);       }     }     vector<long long> to(hors.size(), -1);     vector<long long> used(verts.size(), 0);     vector<long long> from(verts.size(), -1);     function<bool(int)> dfs = [&](int v) {       if (used[v]) return false;       used[v] = 1;       for (int u : g[v]) {         if (to[u] == -1 || dfs(to[u])) {           to[u] = v;           from[v] = u;           return true;         }       }       return false;     };     for (int i = 0; i < verts.size(); i++) {       used.assign(verts.size(), 0);       dfs(i);     }     used.assign(verts.size(), 0);     vector<long long> used1(hors.size(), 0);     function<void(int)> dfs1 = [&](int v) {       if (used[v]) return;       used[v] = 1;       for (int u : g[v]) {         if (!used1[u]) {           used1[u] = 1;           dfs1(to[u]);         }       }     };     vector<long long> free(verts.size(), 1);     for (int i : to)       if (i != -1) free[i] = 0;     for (int i = 0; i < verts.size(); i++)       if (free[i]) dfs1(i);     for (int i = 0; i < verts.size(); i++) {       auto a = verts[i].first, b = verts[i].second;       if (i == 0 || verts[i - 1].second != verts[i].first) {         if (i > 0) v.push_back(verts[i - 1].second);         v.push_back(a);       }       if (!used[i]) v.push_back(a), v.push_back(b);     }     if (!verts.empty()) v.push_back(verts.back().second);     for (int i = 0; i < hors.size(); i++) {       auto a = hors[i].first, b = hors[i].second;       if (i == 0 || hors[i - 1].second != hors[i].first) {         if (i > 0) h.push_back(hors[i - 1].second);         h.push_back(a);       }       if (used1[i]) h.push_back(a), h.push_back(b);     }     if (!hors.empty()) h.push_back(hors.back().second);     cout << h.size() / 2 << endl;     for (int i = 0; i < h.size(); i++)       cout << h[i].first <<     << h[i].second << ((i % 2) ?   n  :    );     cout << v.size() / 2 << endl;     for (int i = 0; i < v.size(); i++)       cout << v[i].first <<     << v[i].second << ((i % 2) ?   n  :    );     return 0;   }   