func_code_string: #include <bits/stdc++.h>   using namespace std;   const int M = 1010;   int n;   vector<pair<int, int> > pt;   vector<int> vx, vy;   vector<int> gx[M], gy[M];   vector<tuple<int, int, int> > sh, sv;   int pa[M], pb[M], ln, lm;   vector<int> v[M];   bool used[M], used1[M];   vector<int> dx[M], dy[M];   bool dfs(int p) {     used[p] = true;     for (int i : v[p]) {       if (pb[i] == -1 || (!used[pb[i]] && dfs(pb[i]))) {         pa[p] = i;         pb[i] = p;         return true;       }     }     return false;   }   void dfs_set(int p) {     used[p] = true;     for (int i : v[p]) {       used1[i] = true;       if (pb[i] != -1 && !used[pb[i]]) dfs_set(pb[i]);     }   }   void kuhn() {     memset(pa, -1, sizeof(pa));     memset(pb, -1, sizeof(pb));     for (int i = 0; i < ln; i++) {       memset(used, 0, sizeof(used));       if (dfs(i)) continue;     }     memset(used, 0, sizeof(used));     memset(used1, 0, sizeof(used1));     for (int i = 0; i < ln; i++)       if (pa[i] == -1) dfs_set(i);     for (int i = 0; i < ln; i++) used[i] = (!used[i]);   }   int main() {     ios::sync_with_stdio(0);     cin >> n;     for (int i = 0; i < n; i++) {       int x, y;       cin >> x >> y;       vx.push_back(x);       vy.push_back(y);       pt.push_back(make_pair(x, y));     }     sort(vx.begin(), vx.end());     vx.resize(unique(vx.begin(), vx.end()) - vx.begin());     sort(vy.begin(), vy.end());     vy.resize(unique(vy.begin(), vy.end()) - vy.begin());     for (int i = 0; i < n; i++) {       pt[i].first = lower_bound(vx.begin(), vx.end(), pt[i].first) - vx.begin();       pt[i].second = lower_bound(vy.begin(), vy.end(), pt[i].second) - vy.begin();     }     for (int i = 0; i < n; i++) {       gx[pt[i].first].push_back(pt[i].second);       gy[pt[i].second].push_back(pt[i].first);     }     for (int i = 0; i < n; i++) sort(gx[i].begin(), gx[i].end());     for (int i = 0; i < n; i++) sort(gy[i].begin(), gy[i].end());     for (int y = 0; y < n; y++)       if ((int)gy[y].size() > 1)         for (int i = 0; i < (int)gy[y].size() - 1; i++)           sh.push_back(make_tuple(gy[y][i], gy[y][i + 1], y));     for (int x = 0; x < n; x++)       if ((int)gx[x].size() > 1)         for (int i = 0; i < (int)gx[x].size() - 1; i++)           sv.push_back(make_tuple(gx[x][i], gx[x][i + 1], x));     sort(sh.begin(), sh.end());     sort(sv.begin(), sv.end());     ln = sh.size();     lm = sv.size();     for (int i = 0; i < ln; i++)       for (int j = 0; j < lm; j++) {         if (!(get<0>(sh[i]) < get<2>(sv[j]) && get<2>(sv[j]) < get<1>(sh[i])))           continue;         if (!(get<0>(sv[j]) < get<2>(sh[i]) && get<2>(sh[i]) < get<1>(sv[j])))           continue;         v[i].push_back(j);       }     kuhn();     for (int y = 0; y < n; y++)       if ((int)gy[y].size() >= 1) dy[y].push_back(gy[y][0]);     for (int x = 0; x < n; x++)       if ((int)gx[x].size() >= 1) dx[x].push_back(gx[x][0]);     for (int i = 0; i < ln; i++)       if (used[i]) {         dy[get<2>(sh[i])].push_back(get<0>(sh[i]));         dy[get<2>(sh[i])].push_back(get<1>(sh[i]));       }     for (int i = 0; i < lm; i++)       if (used1[i]) {         dx[get<2>(sv[i])].push_back(get<0>(sv[i]));         dx[get<2>(sv[i])].push_back(get<1>(sv[i]));       }     for (int y = 0; y < n; y++)       if ((int)gy[y].size() >= 1) dy[y].push_back(gy[y].back());     for (int x = 0; x < n; x++)       if ((int)gx[x].size() >= 1) dx[x].push_back(gx[x].back());     int ans = 0;     for (int y = 0; y < n; y++) ans += (int)dy[y].size();     ans /= 2;     cout << ans <<   n ;     for (int y = 0; y < n; y++)       for (int i = 0; i < (int)dy[y].size(); i += 2)         cout << vx[dy[y][i]] <<     << vy[y] <<     << vx[dy[y][i + 1]] <<                  << vy[y] <<   n ;     ans = 0;     for (int x = 0; x < n; x++) ans += (int)dx[x].size();     ans /= 2;     cout << ans <<   n ;     for (int x = 0; x < n; x++)       for (int i = 0; i < (int)dx[x].size(); i += 2)         cout << vx[x] <<     << vy[dx[x][i]] <<     << vx[x] <<                  << vy[dx[x][i + 1]] <<   n ;     return 0;   }   