#include <fstream.h>
#include <iostream.h>
#include <stdio.h>
using namespace std;
long i,comp_conex=0;
long n,m,vizitat[100005];
typedef struct nod
{     
int info;
      
nod *urm;
} *pNod;
pNod v[100005];
   
void citire()
{int i,j,k,x,y;
   
ifstream f("dfs.in");
   
f>>n>>m;
   
pNod nou;
   
for (i = 1; i <= m; i++)
      
{
       
f>>x>>y;
          
nou=new nod;
          
nou->info=x;
          
nou->urm=v[y];
          
v[y]=nou;
          
nou=new nod;
nou->info=y;
          
nou->urm=v[x];
         
v[x]=nou;
      
}   
f.close();
}
   
   
void df(int nod)
{pNod p;
      
vizitat[nod] = 1;
     
for (p=v[nod];p!=NULL;p=p->urm) if(!vizitat[p->info]) df(p->info);
}
void afisare()
{ofstream g("dfs.out");
g<<comp_conex;
g.close();
}
   
   
int main()
{int j,k,indice=1;
   
citire();
    
   
while(indice!=0)
{indice=0;
for(k=1;k<=n;k++)
    
if(vizitat[k]==0)
    
{indice=1;comp_conex++;df(k);}
}
afisare();
return 0;
}