func_code_string: #include <bits/stdc++.h>   using namespace std;   class Reduced_Indexs {     vector<int> idxs;     int n;       public:     Reduced_Indexs() = default;     template <typename InputIterator>     Reduced_Indexs(InputIterator first, InputIterator last) {       idxs = vector<int>(first, last);       sort(idxs.begin(), idxs.end());       n = unique(idxs.begin(), idxs.end()) - idxs.begin();       idxs.resize(n);     }     int size();     int get_idx(int);     int get_value(int);   };   int Reduced_Indexs::size() { return n; }   int Reduced_Indexs::get_idx(int x) {     auto p = lower_bound(idxs.begin(), idxs.end(), x);     return (p != idxs.end() && *p == x) ? (p - idxs.begin()) : -1;   }   int Reduced_Indexs::get_value(int i) { return idxs[i]; }   const int N = 100000;   const long long MOD = 1000000007LL;   long long pow2[N + 2];   int xs[N], ys[N];   Reduced_Indexs xidxs, yidxs;   vector<int> xeq[N], yeq[N];   bool checked[N];   set<int> xused, yused;   int cnt;   void check(int);   int main() {     pow2[0] = 1LL;     for (int i = 1; i <= N + 1; ++i) {       pow2[i] = (pow2[i - 1] * 2) % MOD;     }     int n;     scanf( %d , &n);     for (int i = 0; i < n; ++i) {       scanf( %d%d , &xs[i], &ys[i]);     }     xidxs = Reduced_Indexs(xs, xs + n);     yidxs = Reduced_Indexs(ys, ys + n);     for (int i = 0; i < n; ++i) {       xeq[xidxs.get_idx(xs[i])].push_back(i);       yeq[yidxs.get_idx(ys[i])].push_back(i);     }     long long ans = 1LL;     for (int i = 0; i < n; ++i) {       xused.clear();       yused.clear();       cnt = 0;       check(i);       int total = xused.size() + yused.size();       ans = (ans * (pow2[total] - (cnt < total))) % MOD;     }     printf( %lld n , ans);     exit(EXIT_SUCCESS);   }   void check(int u) {     if (checked[u]) {       return;     }     checked[u] = true;     ++cnt;     int x = xs[u], y = ys[u];     if (!xused.count(x)) {       xused.insert(x);       for (int v : xeq[xidxs.get_idx(x)]) {         check(v);       }     }     if (!yused.count(y)) {       yused.insert(y);       for (int v : yeq[yidxs.get_idx(y)]) {         check(v);       }     }   }   