#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using Pi = pair<int, int>;
using Pl = pair<ll, ll>;
using Ti = tuple<int, int, int>;
using Tl = tuple<ll, ll, ll>;

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define F first
#define S second
#define Get(t, i) get<(i)>((t))
#define all(v) (v).begin(), (v).end()
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define reps(i, f, n) for(int i = (int)(f); i < (int)(n); i++)
#define each(a, b) for(auto& a : b)

const int inf = 1 << 25;
const ll INF = 1LL << 55;

struct UnionFind
{
  vector<int> data;
  UnionFind(int sz):data(sz, -1){}
  int find(int x)
  {
    return (data[x] < 0 ? x : data[x] = find(data[x]));
  }
  bool same(int x, int y)
  {
    return (find(x) == find(y));
  }
  int unite(int x, int y)
  {
    x = find(x), y = find(y);
    if(x != y) {
      if(data[x] < data[y]) swap(x, y);
      data[x] += data[y]; data[y] = x;
    }
    return -data[x];
  }
  int size(int x)
  {
    return -data[find(x)];
  }
};

int main()
{
  int N, W, H;
  cin >> N >> W >> H;
  UnionFind uf(N);
  vector<int> xx(W, -1), yy(H, -1);
  int hashi = 0;
  rep(i, N) {
    int x, y; cin >> x >> y;
    x--, y--;
    if(x == 0 || x == W-1 || y == 0 || y == H-1) hashi = 1;
    if(~xx[x]) uf.unite(i, xx[x]);
    else xx[x] = i;
    if(~yy[y]) uf.unite(i, yy[y]);
    else yy[y] = i;
  }
  set<int> st;
  rep(i, N) st.insert(uf.find(i));
  if((int)st.size() == 1) cout << N-1 << endl;
  else cout << N+(int)st.size()-1-hashi << endl;
  return 0;
}