#include<stdio.h>
FILE *f,*g;
int n,m,x,y,viz[100002],nr;
struct lista{
	int value;
	lista *next;
};
struct caplista{
	int vec;
	lista *first;
}cap[100002];
void add(int i, int x)
{
	lista *p,*q;
	if(cap[i].first==NULL)
	{
		p=new lista;
		p->value=x;
		p->next=NULL;
		cap[i].first=p;
		cap[i].vec++;
	}
	else 
	{
		cap[i].vec++;
		p=cap[i].first;
		while(p->next)
			p=p->next;
		q=new lista;
		q->value=x;
		q->next=NULL;
		p->next=q;
	}
}
void dfs(int i)
{
	if(!viz[i])
	{
		viz[i]=1;
		lista *p;
		p=cap[i].first;
		while(p)
		{
			dfs(p->value);
			p=p->next;
		}
	}
}
int main()
{
	f=fopen("dfs.in","r");
	g=fopen("dfs.out","w");
	fscanf(f,"%d %d",&n,&m);
	for(;m--;)
	{
		fscanf(f,"%d %d",&x,&y);
		add(x,y);
		add(y,x);
	}
	for(int i=1;i<=n;i++)
	{
		if(!viz[i])
		{
			nr++;
			dfs(i);
		}
	}
	fprintf(g,"%d\n",nr);
	return 0;
}