#include <bits/stdc++.h>

using namespace std;

void fast_io() {
	ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
}

#include <atcoder/maxflow>
using namespace atcoder;
int main() {
	fast_io();
	int n;
	long long m;
	cin >> n >> m;
	vector<long long> x(n), y(n), val;
	for (int i = 0; i < n; i++) {
		cin >> x[i] >> y[i];
		val.push_back(x[i]);
		val.push_back(y[i]);
	}
	sort(val.begin(), val.end());
	val.erase(unique(val.begin(), val.end()), val.end());
	int sz = val.size();
	for (int i = 0; i < n; i++) {
		x[i] = lower_bound(val.begin(), val.end(), x[i]) - val.begin();
		y[i] = lower_bound(val.begin(), val.end(), y[i]) - val.begin();
	}
	mf_graph<int> g(n + sz + 2);
	int s = n + sz, t = s + 1;
	for (int i = 0; i < n; i++) {
		g.add_edge(s, i, 1);
		g.add_edge(i, n + x[i], 1);
		g.add_edge(i, n + y[i], 1);
	}
	for (int i = 0; i < sz; i++) {
		g.add_edge(n + i, t, 1);
	}
	cout << g.flow(s, t) << "\n";
}