#include<fstream>
using namespace std;


ifstream cin("dfs.in");
ofstream cout("dfs.out");

struct nod{
	int val;
	nod *next;
};
bool viz[100005];
int n, m;
nod *l[100005];

void add(int x, int y){
	nod *r, *w;
	r = new nod;	r->val=x;	r->next = NULL;
	w = new nod;	w->val=y;	w->next = NULL;
	
	if(!l[y]) l[y]=r;
	else{		r->next = l[y];		l[y]=r;}
	if(!l[x]) l[x]=w;
	else{	w->next = l[x]; 	l[x]=w;}	
}

void dfs(int i){
	if(!viz[i])	viz[i]=1;
	while(l[i]!=NULL){
		nod *r; r = l[i]; l[i]=l[i]->next; if(!viz[r->val])	viz[r->val]=1;
	dfs(r->val);
}}

int main(){
	cin>>n>>m;
	
	while(m--){
		int x, y;
		cin>>x>>y;
		add(x, y);	}
	int comp=0;
	
	for (int i=1; i<=n; ++i){
		if(viz[i]==0){
			++comp;
			dfs(i);
		}
	}
	
	cout<<comp;
	
	return 0;
}