func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 1e6 + 5;   int n;   pair<int, int> a[N];   void rec(int l, int r) {     if (l >= r) {       return;     }     int mid = (r + l) >> 1;     rec(l, mid);     rec(mid + 1, r);     for (int i = l; i <= r; i++) {       n++;       a[n] = make_pair(a[mid].first, a[i].second);     }   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n;     for (int i = 1; i <= n; i++) {       cin >> a[i].first >> a[i].second;     }     sort(a + 1, a + n + 1);     rec(1, n);     sort(a + 1, a + n + 1);     n = unique(a + 1, a + n + 1) - a - 1;     cout << n <<   n ;     for (int i = 1; i <= n; i++) {       cout << a[i].first <<     << a[i].second <<   n ;     }   }   