#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

void solve(){
    
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; ll m; cin >> n >> m;
    vll x(n), y(n);
    set<ll> st;
    rep(i, n){
        cin >> x[i] >> y[i];
        st.insert(x[i]);
        st.insert(y[i]);
    }
    map<ll, int> mp;
    int itr= 0;
    for(auto i : st){
        mp[i] = itr;
        itr++;
    }
    mf_graph<int> s(n+itr+2);
    rep(i, n){
        s.add_edge(n+itr, i, 1);
        s.add_edge(i, n+mp[x[i]], 1);
        s.add_edge(i, n+mp[y[i]], 1);
    }
    rep(i, itr){
        s.add_edge(n+i, n+itr+1, 1);
    }cout << s.flow(n+itr, n+itr+1) << endl;

    return 0;
}