#include <algorithm>

 #include <cstring>

 #include <cstdio>

 using namespace std;

 const int N();

 int n,m,u,v,ans;

 int head[N],sumedge;

 struct Edge

 {

     int to,next;

     Edge(int to=,int next=) :

         to(to),next(next) {}

 }edge[N<<];

 void ins(int from,int to)

 {

     edge[++sumedge]=Edge(to,head[from]);

     head[from]=sumedge;

 }

 int tim,dfn[N],low[N],vis[N],du[N];

 int sumcol,col[N],colvis[N];

 void DFS(int now,int pre)

 {

     low[now]=dfn[now]=++tim;

     vis[now]=;

     for(int i=head[now];i;i=edge[i].next)

     {

         int go=edge[i].to;

         if(go==pre) continue;

         if(!vis[go])

         {

             DFS(go,now);

             low[now]=min(low[now],low[go]);

         } else if(vis[go]==)

             low[now]=min(low[now],dfn[go]);

     }

     vis[now]=;

 }

 int main()

 {

     scanf("%d%d",&n,&m);

     for(;m;m--)

     {

         scanf("%d%d",&u,&v);

         ins(u,v); ins(v,u);

     }

     for(int i=;i<=n;i++)

         if(!vis[i]) DFS(i,i);

     for(u=;u<=n;u++)

         for(int j=head[u];j;j=edge[j].next)

         {

             v=edge[j].to;

             if(low[u]!=low[v])

                 du[low[u]]++;

         }

     for(int i=;i<=n;i++)

         if(du[i]==) ans++;

     printf("%d\n",(ans+)>>);

     return ;

 }