#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define sar(a,n) {cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl;}

using namespace std;

template<typename S,typename T>auto&operator<<(ostream&o,pair<S,T>p){return o<<"{"<<p.fi<<","<<p.se<<"}";}
template<typename T>auto&operator<<(ostream&o,set<T>s){for(auto&e:s)o<<e<<" ";return o;}
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,priority_queue<S,T,U>q){while(!q.empty())o<<q.top()<<" ",q.pop();return o;}
template<typename K,typename T>auto&operator<<(ostream&o,map<K,T>&m){for(auto&e:m)o<<e<<" ";return o;}
template<typename T>auto&operator<<(ostream&o,vector<T>v){for(auto&e:v)o<<e<<" ";return o;}
void ashow(){cout<<endl;}template<typename T,typename...A>void ashow(T t,A...a){cout<<t<<" ";ashow(a...);}
template<typename S,typename T,typename U>
struct TRI{S fi;T se;U th;TRI(){}TRI(S f,T s,U t):fi(f),se(s),th(t){}
bool operator<(const TRI&_)const{return(fi==_.fi)?((se==_.se)?(th<_.th):(se<_.se)):(fi<_.fi);}};
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,TRI<S,T,U>&t){return o<<"{"<<t.fi<<","<<t.se<<","<<t.th<<"}";}

typedef pair<int, int> P;
typedef pair<ll, ll> pll;
typedef TRI<int, int, int> tri;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<P> vp;
typedef vector<double> vd;
typedef vector<string> vs;

const int MAX_N = 100005;

class MergeTech{
private:
    int sz;
public:
    vector<int> par;              //所属しているグループ番号(par[x] は union find の find(x) に対応)
    vector<vector<int> > group;   //group[x]: グループ x に含まれる数
    MergeTech(){}
    MergeTech(int node_size) : sz(node_size), par(sz), group(sz){
        for(int i = 0; i < sz; i++){
            par[i] = i, group[i].push_back(i);
        }
    }
    bool same(int a,int b){ return par[a] == par[b]; }
    void unite(int a,int b){
        if(same(a,b)) return;
        if(group[par[a]].size() < group[par[b]].size()) swap(a,b);
        int ga = par[a], gb = par[b];
        for(int u : group[gb]){
            par[u] = ga;
        }
        group[ga].insert(group[ga].end(),group[gb].begin(),group[gb].end());
        group[gb].clear();
    }
};

vector<int> hor[MAX_N];
int prv[MAX_N];

int main()
{
    int n;
    cin >> n;
    rep(i,MAX_N) prv[i] = -1;
    rep(i,n){
        int x, y;
        cin >> x >> y;
        hor[x-1].pb(y);
    }
    MergeTech uf(MAX_N);
    rep(i,MAX_N){
        if(hor[i].empty()) continue;
        for(const int y : hor[i]){
            if(prv[y] >= 0){
                uf.unite(prv[y], i);
            }
            prv[y] = i;
        }
    }
    long long ans = 0;
    const auto& g = uf.group;
    for(const vector<int>& vec : g){
        set<int> st;
        for(const int x : vec){
            for(const int y : hor[x]){
                st.insert(y);
            }
        }
        ans += (long long)vec.size() * (int)st.size();
    }
    cout << ans - n << "\n";
}

Measured memory_bytes: 13940