#include<fstream>
#define NMAX 100010

using namespace std;

ifstream f("dfs.in");
ofstream g("dfs.out");

struct nod
{
	int x;
	nod *leg;
} *a[NMAX], *ultim[NMAX];
int n, m, nr[NMAX], vz[NMAX];

void Adauga(int x, int y)
{
	nod *q;
	++nr[x];
	if (nr[x]==1)
	{
		a[x]=ultim[x]=new nod;
		a[x]->leg=NULL; a[x]->x=y;
	}
	else
	{
		q=new nod; q->leg=NULL;
		q->x=y;
		ultim[x]->leg=q; ultim[x]=q;
	}
}

void Citeste()
{
	int i, x, y;
	
	f>>n>>m;
	for (i=1; i<=m; ++i)
	{
		f>>x>>y;
		Adauga(x, y);
		Adauga(y, x);
	}
}

void DFS(int x)
{
	nod *p;
	vz[x]=1;
	p=a[x];
	while (p)
	{
		if (!vz[p->x]) DFS(p->x);
		p=p->leg;
	}
}

void Solve()
{
	int i, nr=0;
	for (i=1; i<=n; ++i)
		if (!vz[i]) DFS(i), ++nr;
	g<<nr<<"\n";
}

int main()
{
	Citeste();
	Solve();
	f.close();
	g.close();
	return 0;
}