/**
	author:  shobonvip
	created: 2025.02.14 21:31:06
**/

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

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)
#define all(v) v.begin(), v.end()

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

// defcomp
template <typename T>
vector<T> compress(vector<T> &X) {
	vector<T> vals = X;
	sort(vals.begin(), vals.end());
	vals.erase(unique(vals.begin(), vals.end()), vals.end());
	return vals;
}
// -----

// importbisect
template <typename T>
int bisect_left(vector<T> &X, T v){
	return lower_bound(X.begin(), X.end(), v) - X.begin();
}

template <typename T>
int bisect_right(vector<T> &X, T v){
	return upper_bound(X.begin(), X.end(), v) - X.begin();
}
// -----


int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	int n; ll m;
	cin >> n >> m;
	vector<ll> x(n),y(n);
	vector<ll> v;
	rep(i,0,n){
		cin>>x[i]>>y[i];
		v.push_back(x[i]);
		v.push_back(y[i]);
	}
	v = compress(v);
	rep(i,0,n){
		x[i]=bisect_left(v,x[i]);
		y[i]=bisect_left(v,y[i]);
	}
	int k=v.size();
	dsu uf(k);
	vector<int> order(k);
	rep(i,0,n){
		uf.merge(x[i],y[i]);
	}
	rep(i,0,n){
		order[uf.leader(x[i])]++;
	}
	int ans=0;
	rep(i,0,k){
		if(uf.leader(i)==i){
			int sz = uf.size(i);
			ans+=min(sz,order[i]);
		}
	}
	cout<<ans<<endl;
}