#include <bits/stdc++.h>

using namespace std;

const int NMAX = 8091;

vector <int> edges[2 * NMAX + 1];
int viz[2 * NMAX + 1];
int match[4 * NMAX + 1];

bool bfs( int node ) {
    viz[node] = 1;
    for ( auto it : edges[node] ) {
        int x = match[it];
        if ( x == 0 ) {
            match[node] = it;
            match[it] = node;
            return 1;
        }
        if ( !viz[x] && bfs( x ) ) {
            match[node] = it;
            match[it] = node;
            return 1;
        }
    }
    return 0;
}
int cuplaj( int n ) {
    int cnt = 0, ok = 1;
    while ( ok ) {
        ok = 0;
        memset( viz, 0, sizeof(viz) );
//        memset( match, 0, sizeof(match) );
        for ( int i = 1; i <= n; i ++ ) {
            if ( !viz[2 * i] && !match[2 * i] && bfs( 2 * i ) ) {
                cnt ++;
                ok = 1;
            }
        }
    }
    return cnt;
}
int main() {
    ifstream fin( "felinare.in" );
    ofstream fout( "felinare.out" );
    int n, m, i, a, b;
    fin >> n >> m;
    for ( i = 0; i < n; i ++ ) {
        fin >> a >> b;
        edges[2 * a].push_back( 2 * b - 1 );
        edges[2 * b - 1].push_back( 2 * a );
//        cout << 2 * a << ' ' << 2 * b - 1 << endl;
    }
    fout << 2 * n - cuplaj( n ) << '\n';

    return 0;
}