//Parcurgerea dfs . Sa se afiseze numarul componentelor conexe .
//Graful e retinut prin liste de adiacenta alocate dinamic.
//Coada e retinuta dinamic .
#include<fstream>
#define nmax 100001

using namespace std;

ifstream fin("dfs.in");
ofstream fout("dfs.out");

int n,m,viz[nmax];

struct nod
   {int inf;
    struct nod *urm;
   };
nod *l[nmax];

void citire()
{int i,x,y;
fin>>n>>m;
for(i=1;i<=m;i++)
   {fin>>x>>y;
    nod *c;
    c=new nod;
    c->inf=y;
    c->urm=l[x];
    l[x]=c;
    c=new nod;
    c->inf=x;
    c->urm=l[y];
    l[y]=c;
   }
}

void adaugare_in_coada(int x,nod *&prim,nod *&ultim)
{nod *nou;
nou=new nod;
nou->inf=x;
nou->urm=NULL;
if(prim==NULL)
   prim=nou;
 else ultim->urm=nou;
ultim=nou;
}

void stergere(nod *&prim,nod *&ultim)
{nod *c;
c=prim;
prim=prim->urm;
delete c;
if(prim==NULL)
   ultim=NULL;
}

void dfs(int i,int nr)
{nod *prim=NULL,*ultim=NULL,*c;
int aux;
adaugare_in_coada(i,prim,ultim);
do{aux=prim->inf;
  stergere(prim,ultim);
  for(c=l[aux];c!=NULL;c=c->urm)
    if(viz[c->inf]==0)
      {adaugare_in_coada(c->inf,prim,ultim);
       viz[c->inf]=nr;
      }
  }while(prim!=NULL);
}

int main()
{int i,nr=0;
citire();
for(i=1;i<=n;i++)
   if(viz[i]==0)
     {nr++;
      dfs(i,nr);
     }
fout<<nr;
fin.close();
fout.close();
return 0;
}