using namespace std;

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <vector>
#include <iostream>
#include <cmath>
#include <cassert>

#define NDEBUG

#define FIN "felinare.in"
#define FOUT "felinare.out"

#define maxn 8192


#ifndef NDEBUG
int stp;
#endif



vector<vector<short> > x;
vector<vector<bool> > a;
//char aa[maxn+2000][(maxn/8) +2000];

int n, m, E;
short source, sink;
short t[maxn<<1];
short d[maxn<<1];
bool Viz[maxn<<1];
int bfs();
void solve();

void read()
{

	int i,p, q;
		scanf("%d %d\n", &n, &m);
		a.clear();
		x.clear();
		
		a.resize(n+n+2);
		for(i=0;i<n+n+2;i++) a[i].resize(n+n+2);
		source=0;
		sink=n+n+1;
		x.resize(n+n+2);
		for(i=0;i<m;++i)
		{
			scanf("%d %d\n", &p, &q);
			a[p][q+n]=1;
	
			x[p].push_back(q+n);
			x[q+n].push_back(p);
			
		}
		for(i=1;i<=n;++i)a[source][i]=1, x[source].push_back(i), x[i].push_back(source);
		for(i=n+1;i<sink;++i) a[i][sink]=1, x[i].push_back(sink), x[sink].push_back(i);
		
		

		
}


int bfs()
{
	short Q[maxn<<1], p=1, q=1;
	bool viz[maxn<<1];
	short d[maxn<<1];
	memset(viz, 0,sizeof(viz));
	//memset(t, -1, sizeof(t));
	memset(d, 0, sizeof(d));
	viz[source]=1;
	Q[1]=source;
	d[1]=0;
	int u;
	short i;
	vector<short>::iterator it, xu;
	
	while(p<=q)
	{
		u=Q[p++];
		xu=x[u].end();
		for(it=x[u].begin();it!=xu;++it)
		{
		  i=*it;
		  if(!viz[i] && a[u][i])//(aa[u][(i)>>3]&(1<<((i)&7))))
			{
				viz[i]=1;
				d[i]=d[u]+1;
				//	t[i]=u;
				Q[++q]=i;
					if(i==sink) return d[i];
			}
		}
	}
	
	if(d[sink]==0) return 0;
	return d[sink];
}



int flow, ok=1, dsink,nr;


void dfs2(short nd, short nr)
{

  //printf("%d %d\n",nd, nr);
	if(nr>dsink) return;

	if(nd==sink) { ++flow; ok=0; return;}
	//	if(nd==source) ok=1;
	
	Viz[nd]=1;

	vector<short>::iterator it, xnd;
	short i;
	xnd=x[nd].end();
	for(it=x[nd].begin(); it!=xnd; ++it)
	{
	   i=*it;
	   if(ok &&  !Viz[i]  && a[nd][i])
	     {
			dfs2(i, nr+1);
			
			if(!ok)
			{
			  a[nd][i]=0;
			  a[i][nd]=1;
			    if(nd==source) ok=1;
			   else
			    break;
			}
			//		if(nd==source) ok=1;
	     }
	}
}
	


void solve()
{
	int i, j;
	int p;
	
	flow=0;
	vector<short>::iterator it;
	int num=0;
	int sq=(int)sqrt(n+n)+3;
	while(dsink=bfs())
	{
	
	  ++num;
	  //	  	  printf("(%d)\n", dsink);
	  memset(Viz, 0, sizeof(Viz));
		ok=1;
		nr=0;
		//dsink=d[sink];	
		dfs2(source, 0);



	}
	printf("%d\n", 2*n-flow);
	//printf("%d %d %d\n",(int) sqrt(n), nr, n);
	//	printf("(%d)\n", n);
	//intf("(%d)\n", (int)sqrt(n));
	//printf("(%d)\n", num);
}






int main()
{
  //  freopen("fel.in", "r", stdin);
  freopen(FIN, "r", stdin);
	       	freopen(FOUT, "w", stdout);

	read();
	solve();
	
	return 0;
}