#include<cstdio>
#include<deque>
#include<iostream>
using namespace std;
const int SIZEN=100010,SIZEM=500010,INF=0x7fffffff/2;
int N,M,tot=0,d[SIZEN]={0};
deque<int> s[SIZEN];
int ans=INF;
class miku
{
    public:
	int fr,to;
	bool t;
	miku(){}
	miku(int a,int b,int c)
	{
		fr=a,to=b,t=c;
	}
}E[SIZEM*2];
void add(int fr,int to)
{
	s[fr].push_back(tot);
	E[tot++]=miku(fr,to,0);
	s[to].push_back(tot);
	E[tot++]=miku(to,fr,0);
	d[fr]++;d[to]++;
}
void read()
{
	scanf("%d%d",&N,&M);
	int fr,to;
	for(int i=1;i<=M;i++)
	{
		scanf("%d%d",&fr,&to);
		add(fr,to);
	}
}
void dfs(int x,int now)
{
	if(now>=ans) return;
	//cout<<x<<" "<<d[x]<<endl;
	if(d[x]==0)
	{
		int flag=0;
		for(int i=1;i<=N;i++)
		{
			if(d[i]!=0)
			{
				dfs(i,now+1);
				flag=1;
			}
		}
		if(!flag) ans=now;
		return;
	}
	for(int i=0;i<s[x].size();i++)
	{
		//cout<<x<<endl;
		miku &v=E[s[x][i]];
		//cout<<v.fr<<" "<<v.to<<endl;
		if(v.t==1) continue;
		v.t=1;E[s[x][i]^1].t=1;d[v.fr]--;d[v.to]--;
		dfs(v.to,now);
		v.t=0;E[s[x][i]^1].t=0;d[v.fr]++;d[v.to]++;
	}
	//cout<<"*****"<<endl;
}
void work()
{
	dfs(1,0);
	printf("%d",ans);
}
int main()
{
	freopen("sent.in","r",stdin);
	freopen("sent.out","w",stdout);
	read();
	work();
	return 0;
}