func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   vector<pair<int, int> > a;   set<pair<int, int> > d;   void solve(int l, int r) {     if (r - l <= 1) return;     int m = (l + r) / 2;     solve(l, m);     solve(m, r);     for (int i = l; i < r; ++i) {       d.insert({a[m].first, a[i].second});     }   }   signed main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     int n;     cin >> n;     a.resize(n);     for (int i = 0; i < n; ++i) {       cin >> a[i].first >> a[i].second;       d.insert(a[i]);     }     sort(a.begin(), a.end());     solve(0, n);     cout << d.size() <<   n ;     for (auto i : d) {       cout << i.first <<     << i.second <<   n ;     }   }   