#include<fstream>
using namespace std;
long x,y,n,i,m,nr;
struct nod{int info;nod *adr;} *v[100002];
short viz[200002]; 
void df(int nod)
{
	viz[nod]=1;
	while(v[nod])
	{
	   if(!viz[v[nod]->info])       df(v[nod]->info);
	       v[nod]=v[nod]->adr;
	}
}

int main()
{
	ifstream f("dfs.in");ofstream g("dfs.out");
	f>>n>>m;
	for(i=1;i<=m;i++)
	{f>>x>>y;
	 //add nod
                  nod *p=new nod;	p->info=y;	p->adr=v[x];	v[x]=p;
                  nod *q=new nod;	q->info=x;	q->adr=v[y];	v[y]=q;
	}
	for(i=1;i<=n;i++)
		if(!viz[i]) { nr++; df(i); }
		g<<nr;
	f.close();g.close();
return 0;}