#include<bits/stdc++.h>
using namespace std;

typedef pair<int,int> P;
int N;
int W,H;
vector<int> Y[100005];
vector<int> T[100005];


struct uni {
  int d[ 50000 ];
  void init(){ memset( d,-1,sizeof( d ) ); }
  int find( int a ) { return d[a]<0?a:(d[a] = find( d[a] )); }
  void merge( int a,int b ){
    a = find(a); b = find(b);
    if( a == b ) return;
    if( d[a] > d[b] ) swap( a, b );
    d[a] += d[b]; d[b] = a;
  }
  int size(int a){ return -d[find(a)]; }
};

uni U;
bool used[ 50000 ];
int main(){
  cin >> N >> W >> H;
  int hj = 0;
  for(int i=0;i<N;i++){
    int x,y; cin >> x >> y;
    if( x == 1 || x == W || y == 1 || y == H ) hj=1;
    Y[ y ].push_back( i );
    T[ x ].push_back( i );
  }
  
  U.init();
  for(int i=1;i<=W;i++) {
    for(int j=1;j<(int)T[i].size();j++)
      U.merge( T[i][j-1], T[i][j] );
  }
  for(int i=1;i<=H;i++)
    for(int j=1;j<(int)Y[i].size();j++)
      U.merge( Y[i][j-1], Y[i][j] );


  int cnt = 0;
  int res = 0;
  for(int i=0;i<N;i++){
    int a = U.find( i );
    if( used[ a ] ) continue;
    used[ a ] = true;
    res += U.size( a )-1;
    cnt++;
  }
  if( cnt == 1 ) cout << res << endl;
  else cout << res + cnt + cnt-1 - hj << endl;
}