#include <fstream>
#include <cstring>
#include <vector>
#define Nmax 10009
using namespace std;
ifstream f("felinare.in");
ofstream g("felinare.out");

int N,st[Nmax],dr[Nmax],viz[Nmax],sol;
vector < int > G[Nmax];

void ReadInput()
{
    int M,x,y;
    f>>N>>M;
    for(int i=1;i<=M;++i)
        f>>x>>y , G[x].push_back(y);
}

bool Cupleaza(int node)
{
    if(viz[node])return 0;
    viz[node]=1;
    for(vector<int>::iterator it=G[node].begin();it!=G[node].end();++it)
        if(!dr[*it])
        {
            st[node]=*it;
            dr[*it]=node;
            return 1;
        }
    for(vector<int>::iterator it=G[node].begin();it!=G[node].end();++it)
        if(Cupleaza(dr[*it]))
        {
            st[node]=*it;
            dr[*it]=node;
            return 1;
        }
    return 0;
}

int main()
{
    ReadInput();
    int gata=0;
    while(!gata)
    {
        gata=1;
        memset(viz,0,sizeof(viz));
        for(int i=1;i<=N;++i)
            if(!st[i] && Cupleaza(i))++sol ,gata=0;
    }
    g<<2*N-sol<<'\n';
    f.close();g.close();
    return 0;
}