#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;
}