#include <fstream>
#include <vector>
#include <iostream>
#define DIM 8200

using namespace std;

ifstream fin("felinare.in");
ofstream fout("felinare.out");

int N,M,nr,ok,felinare;
vector <int> L[DIM],r(DIM),l(DIM),v(DIM),ans(DIM);

int cuplaj(int nod){
    v[nod]=1;

    for(int i=0;i<L[nod].size();i++)
        if(r[L[nod][i]]==0){
            r[L[nod][i]]=nod;
            l[nod] = L[nod][i];
            return 1;
        }

    for(int i=0;i<L[nod].size();i++)
        if(v[r[L[nod][i]]]==0 && cuplaj(r[L[nod][i]])){
            l[nod] = L[nod][i];
            r[L[nod][i]] = nod;
            return 1;
        }

    return 0;
}

int main(){

    fin >> N >> M;

    while(M--){
        int x,y;
        fin >> x >> y;
        L[x].push_back(y);
    }

    do{
        ok=0;
        for(int i=1;i<=N;i++)
            v[i]=0;

        for(int i=1;i<=N;i++)
            if(!l[i] && cuplaj(i)){
                nr++;
                ok=1;
            }
    }while(ok);


    for(int i=1;i<=N;i++){
        if(l[i] && !r[i])
            felinare+=2;
        if(!l[i] && !r[i])
            felinare+=2;
        if(!l[i] && r[i])
            felinare+=2;
    }


    fout << felinare << "\n";

}