# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
ll MOD(ll x, ll m){return (x%m+m)%m; }
ll FLOOR(ll x, ll m) {ll r = (x%m+m)%m; return (x-r)/m; }
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        (wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((ll)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
# define eb emplace_back
# define exists(c, e)         ((c).find(e) != (c).end())

struct INIT{
	INIT(){
		std::ios::sync_with_stdio(false);
		std::cin.tie(0);
		cout << fixed << setprecision(20);
	}
}INIT;

namespace mmrz {
	void solve();
}

int main(){
	mmrz::solve();
}
#define debug(...) (static_cast<void>(0))

using namespace mmrz;


template<typename T>
struct dinic {

	struct edge{
		int to;
		T cap;
		T rev;
	};
		
	int n;
	vector<vector<edge>> G;
	vector<int> level;
	vector<int> iter;

	dinic(int _v) : n(_v), G(n), level(n), iter(n) {}

	void add_edge(int from, int to, T cap){
		G[from].push_back((edge){to, cap, (T)G[to].size()});
		G[to].push_back((edge){from, 0, (T)(G[from].size() - 1)});
	}

	void bfs(int s){
		for(int i = 0;i < n;i++)level[i] = -1;
		queue<int> que;
		level[s] = 0;
		que.push(s);
		while(!que.empty()){
			int v = que.front();
			que.pop();
			for(int i = 0;i < (int)G[v].size();i++){
				edge &e = G[v][i];
				if(e.cap > 0 && level[e.to] < 0){
					level[e.to] = level[v] + 1;
					que.push(e.to);
				}
			}
		}
	}

	T dfs(int v, int t, T f){
		if(v == t)return f;
		for(int &i = iter[v];i < (int)G[v].size();i++){
			edge &e = G[v][i];
			if(e.cap > 0 && level[v] < level[e.to]){
				T d = dfs(e.to, t, min(f, e.cap));
				if(d > 0){
					e.cap -= d;
					G[e.to][e.rev].cap += d;
					return d;
				}
			}
		}
		return 0;
	}

	T calc(int s, int t){
		T flow = 0;
		for(;;){
			bfs(s);
			if(level[t] < 0)return flow;
			for(int i = 0;i < n;i++)iter[i] = 0;
			int f;
			while((f = dfs(s, t, inf<T>())) > 0) {
				flow += f;
			}
		}
	}
};

void SOLVE(){
	ll n, m;
	cin >> n >> m;
	vector<ll> x(n), y(n);
	rep(i, n)cin >> x[i] >> y[i];
	{
		vector<ll> v;
		rep(i, n)v.pb(x[i]);
		rep(i, n)v.pb(y[i]);
		sort(all(v));
		UNIQUE(v);
		map<ll, int> mp;
		rep(i, len(v))mp[v[i]] = i;
		rep(i, n)x[i] = mp[x[i]];
		rep(i, n)y[i] = mp[y[i]];
		m = len(v);
	}
	int S = n+m+1, T = n+m+2;
	dinic<int> max_flow(n+m+3);
	rep(i, n){
		max_flow.add_edge(S, i, 1);
	}
	rep(i, n){
		max_flow.add_edge(i, n+x[i], 1);
		max_flow.add_edge(i, n+y[i], 1);
	}
	rep(i, m){
		max_flow.add_edge(n+i, T, 1);
	}
	cout << max_flow.calc(S, T) << '\n';
}

void mmrz::solve(){
	int t = 1;
	//cin >> t;
	while(t--)SOLVE();
}