#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
// 関数ver
template<typename T>
std::pair<std::vector<T>, int> compression(std::vector<T>org) {
	auto copy = org;
	std::sort(copy.begin(), copy.end());
	copy.erase(unique(copy.begin(), copy.end()), copy.end());
	for (auto &e : org) {
		e = std::lower_bound(copy.begin(), copy.end(), e) - copy.begin();
	}
	return { org,copy.size() };
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n, m; cin >> n >> m;
	vector<long long>xy(n * 2);
	rep(i, n)cin >> xy[i * 2] >> xy[i * 2 + 1];
	auto[c, k] = compression(xy);
	int st = n + k;
	int ed = st + 1;
	mcf_graph<int, long long>g(ed + 1);
	rep(i, n) {
		g.add_edge(st, i, 1, 1);
		g.add_edge(i, n + c[i * 2 + 0], 1, 1);
		g.add_edge(i, n + c[i * 2 + 1], 1, 1);
	}
	rep(i, k) {
		g.add_edge(n + i, ed, 1, 1);
	}
	auto [f,_] = g.flow(st,ed);
	cout << f << endl;
	return 0;
}