#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;

// Coodinate Compression
// https://youtu.be/fR3W5IcBGLQ?t=8550
template<typename T=int>
struct CC {
  bool initialized;
  vector<T> xs;
  CC(): initialized(false) {}
  void add(T x) { xs.push_back(x);}
  void init() {
    sort(xs.begin(), xs.end());
    xs.erase(unique(xs.begin(),xs.end()),xs.end());
    initialized = true;
  }
  int operator()(T x) {
    if (!initialized) init();
    return upper_bound(xs.begin(), xs.end(), x) - xs.begin() - 1;
  }
  T operator[](int i) {
    if (!initialized) init();
    return xs[i];
  }
  int size() {
    if (!initialized) init();
    return xs.size();
  }
};

int main(){
	int N;
	long long M;
	cin >> N >> M;
	CC<long long> cc;
	vector<pair<long long, long long>> target;
	rep(i, N){
		long long l, r;
		cin >> l >> r;
		target.emplace_back(l, r);
		cc.add(l);
		cc.add(r);
	}
	int K = cc.size();
	atcoder::mf_graph<int> graph(N + K + 2);
	int sv = N + K;
	int tv = N + K + 1;
	rep(i, N) graph.add_edge(sv, i, 1);
	rep(i, N){
		auto [l, r] = target[i];
		graph.add_edge(i, N + cc(l), 1);
		graph.add_edge(i, N + cc(r), 1);
	}
	rep(x, K) graph.add_edge(N + x, tv, 1);
	int ans = graph.flow(sv, tv);
	cout << ans << "\n";
	return 0;
}