#include<fstream.h>
#define dim 100001
ifstream f("dfs.in");
ofstream g("dfs.out");
int comp[dim],aux[dim];
int main()
{unsigned long n,m;
int x,y,j,cont=0,i;

f>>n>>m;
for(i=1;i<=n;i++) comp[i]=i;
for(i=1;i<=m;i++)
 {f>>x>>y;
  if(x<y)
   {comp[y]=x;
    for(j=1;j<=n;j++)
     if(comp[j]==y) comp[j]=x;
   }
   else
      {comp[y]=x;
       for(j=1;j<=n;j++)
       if(comp[j]==y) comp[j]=x;
      }
 }
f.close();

for(i=1;i<=n;i++)
 if(!aux[comp[i]]) {aux[comp[i]]=1;cont++;}

g<<cont<<'\n';
g.close();
return 0;
}