#include<iostream>

 #include<cstdio>

 #include<algorithm>

 #include<cmath>

 #include<string>

 using namespace std;

 const int N=;

 int n,m,fa[N],vis[N],deg[N],flag[N],num,anss,ans;

 int find(int x){

     if(fa[x]==x)return x;

     else return fa[x]=find(fa[x]);

 }

 void merge(int x,int y){

     int a=find(x);

     int b=find(y);

     if(a==b)return;

     fa[a]=b;

 }

 int main(){

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

     for(int i=;i<=n;i++)fa[i]=i;

     vis[]=;

     for(int i=,a,b;i<=m;i++){

         scanf("%d%d",&a,&b);

         if(a!=b){

             deg[a]++;deg[b]++;

             vis[a]=vis[b]=;

             merge(a,b);

         }

         else vis[a]=;

     }

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

         if(deg[i]&){

             flag[find(i)]++;

         }

     }

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

         if(vis[i]&&i==find(i)){

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

             else anss++;

             num++;

         }

     ans/=;

     if(num==)printf("%d",ans);

     else printf("%d",ans+anss);

     return ;

 }