#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5,inf=1e8;
int tid,test,n,m,S,T,d[N],du[N];
int hd[N],cur[N],to[N],nx[N],w[N],num=1;
void add(int x,int y,int z){
	nx[++num]=hd[x],hd[x]=num,to[num]=y,w[num]=z;
	nx[++num]=hd[y],hd[y]=num,to[num]=x,w[num]=0;
}
bool bfs(){
	queue<int>q;
	for(int i=1;i<=T;++i)d[i]=0;
	d[S]=1,q.push(S);
	while(!q.empty()){
		int u=q.front();
		q.pop();
		for(int i=hd[u],v;v=to[i],i;i=nx[i])if(w[i]&&!d[v]){
			d[v]=d[u]+1;
			if(v==T)return true;
			q.push(v);
		}
	}
	return false;
}
int dinic(int nw,int flow){
	if(nw==T)return flow;
	int rest=flow,k;
	for(int &i=cur[nw];i;i=nx[i])if(w[i]&&d[to[i]]==d[nw]+1){
		k=dinic(to[i],min(w[i],rest));
		if(!k)d[to[i]]=0;
		w[i]-=k,w[i^1]+=k,rest-=k;
		if(!rest)return flow;
	}
	return flow-rest;
}
void solve(){
	scanf("%d%d",&n,&m);
	S=2*n+1,T=S+1;
	for(int i=1;i<=T;++i)hd[i]=0;
	num=1;
	for(int i=1;i<=n;++i)du[i]=0,add(S,i,1),add(i+n,T,1);
	for(int i=1,x,y;i<=m;++i){
		scanf("%d%d",&x,&y);
		++du[x],++du[y];
		add(x,y+n,1);
		add(y,x+n,1);
	}
	int ct=0,maxflow=0;
	for(int i=1;i<=n;++i)if(!du[i])++ct;
	while(bfs()){
		for(int i=1;i<=T;++i)cur[i]=hd[i];
		maxflow+=dinic(S,inf);
	}
	if(maxflow==n-1&&ct==1)--maxflow;
	printf("%d\n",2*maxflow-n);
}
int main(){
	test=1;
	//scanf("%d%d",&tid,&test);
	while(test--)solve();
	return 0;
}