#include<fstream>
#include<vector>

using namespace std;

vector<int> a[100001];
int viz[100001];
int n,m,i,j,x,y,nrcc;
bool posibil;

int urm(int nrcc)
{
	int ok=-1,i;
	for (i=1;i<=n;i++)
		if (viz[i]==0) {ok=i;break;}
	return ok;
}

void dfs(int x)
{
	viz[x]=1;
	int i;
	for (i=0;i<a[x].size();i++)
	if (viz[a[x][i]]==0) dfs(a[x][i]);
}
	
int main(){
	
	ifstream f("dfs.in");
	ofstream g("dfs.out");
	
	f>>n>>m;
	
	for (i=0;i<n;++i)
	{
		f>>x>>y;
		a[x].push_back(y);
		a[y].push_back(x);
	}
	nrcc=0;
	posibil=true;
	do{
		x=urm(nrcc);
		if (x==-1) posibil
			=false;
		else ++nrcc;
		dfs(x);
	}while(posibil);
	
	g<<nrcc<<"\n";
	f.close();
	g.close();
	return 0;
}