Language: C++

#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <numeric>
#include <sstream>
#include <iostream>
#include <iomanip>
#define _USE_MATH_DEFINES
#include <cmath>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cfloat>
#include <cmath>
#include <ctime>
#include <cassert>
#include <cctype>
#include <cstdio>
#include <cassert>
using namespace std;
 
#define EPS 1e-12
#define ull unsigned long long
#define ll long long
#define VI vector<ll>
#define PII pair<ll, ll> 
#define VVI vector<vector<ll> >
#define VVVI vector<vector<vector<ll>>>
#define VVVVI vector<vector<vector<vector<ll>>>>
#define REP(i,n) for(ll i=0,_n=(n);(i)<(ll)_n;++i)
#define REPR(i,n) for(ll i=(ll)(n)-1;0<=(i);--i)
#define RANGE(i,a,b) for(ll i=(ll)a,_b=(ll)(b);(i)<_b;++i)
#define RANGER(i,a,b) for(ll i=(ll)(b)-1,_a=(ll)(a);(_a)<=i;--i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define ALLR(c) (c).rbegin(), (c).rend()
#define PB push_back
#define MP(a, b) make_pair(a, b)
#define POPCOUNT __builtin_popcount
#define POPCOUNTLL __builtin_popcountll
#define CLEAR(table, v) memset(table, v, sizeof(table));
#define UNIFORM_DOUBLE(a, b) (((b-a)*(double)rand()/RAND_MAX)+a) // [a, b) 
#define UNIFORM_LL(a, b) (ll)UNIFORM_DOUBLE(a, b) // [a, b) 
#define IN(v, lo, hi) ((lo)<=(v) && (v)<(hi))
#define DD(v) cout<<#v<<": "<<v<<endl
#define FI first
#define SE second
template <typename T0, typename T1> std::ostream& operator<<(std::ostream& os, const map<T0, T1>& v) { for( typename map<T0, T1>::const_iterator p = v.begin(); p!=v.end(); p++ ){os << p->first << ": " << p->second << " ";} return os; }
template <typename T0, typename T1> std::ostream& operator<<(std::ostream& os, const pair<T0, T1>& v) { os << v.first << ": " << v.second << " "; return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const vector<T>& v) { for( int i = 0; i < (int)v.size(); i++ ) { os << v[i] << " "; } return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const set<T>& v) { vector<T> tmp(v.begin(), v.end()); os << tmp; return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const deque<T>& v) { vector<T> tmp(v.begin(), v.end()); os << tmp; return os; }
template <typename T> std::ostream& operator<<(std::ostream& os, const vector<vector<T> >& v) { for( int i = 0; i < (int)v.size(); i++ ) { os << v[i] << endl; } return os; }
template<typename T>void maxUpdate(T& a, T b) {a = max(a, b);}
template<typename T>void minUpdate(T& a, T b) {a = min(a, b);}
 
#define MOD 1000000007LL
#define INF (1LL<<60)
 
struct UnionFind {
	vector<int> data;
	UnionFind(int size) : data(size, -1) { }
	bool unite(int x, int y) {
		x = root(x); y = root(y);
		if (x != y) {
			if (data[y] < data[x]) swap(x, y);
			data[x] += data[y]; data[y] = x;
		}
		return x != y;
	}
	bool same(int x, int y) { return root(x) == root(y); }
	int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
	int size(int x) { return -data[root(x)]; }
};
 
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll N;
	while(cin>>N) {
		ll M = 100000;
		VI X(N), Y(N);
		VI LX(M), LY(M);
//		VVI esx(M), esy(M);
		REP(i, N) {
			cin>>X[i]>>Y[i];
			esx[X[i]].PB(Y[i]);
			esy[Y[i]].PB(X[i]);
		}
		UnionFind ux(M), uy(M);
//		REP(i, M) REP(j, esx[i].size()) uy.unite(esx[i][0], esx[i][j]);
//		REP(i, M) REP(j, esy[i].size()) ux.unite(esy[i][0], esy[i][j]);
		REP(i, N) {
			if(LY[X[i]]) {
				uy.unite(LY[X[i]], Y[i]);
//				cout<<"UNITE Y "<<LY[X[i]]<<" "<<Y[i]<<endl;
			}
			LY[X[i]]=Y[i];
			if(LX[Y[i]]) {
				ux.unite(LX[Y[i]], X[i]);
//				cout<<"UNITE X "<<LX[Y[i]]<<" "<<X[i]<<endl;
			}
			LX[Y[i]]=X[i];
		}
		set<PII> vis;
		ll ans = 0;
		REP(i, N) {
			ll rx = ux.root(X[i]);
			ll ry = uy.root(Y[i]);
			if(!vis.count(MP(rx, ry))) {
				vis.insert(MP(rx, ry));
//				cout<<"ADD "<<ux.size(X[i])<<" "<<uy.size(Y[i])<<endl;
				ans += ux.size(rx) * uy.size(ry);
			}
		}
		ans -= N;
		
		cout<<ans<<endl;
//		break;
	}
	
	return 0;
}



Compiler output:
a.cc: In function 'int main()':
a.cc:89:25: error: 'esx' was not declared in this scope
   89 |                         esx[X[i]].PB(Y[i]);
      |                         ^~~
a.cc:90:25: error: 'esy' was not declared in this scope
   90 |                         esy[Y[i]].PB(X[i]);
      |                         ^~~