#include<stdio.h>
#include<stdlib.h>
int n,m;
int *a[100001],cati[100001],rez;
bool ok[100001];
void citire()
{
	int x,y;
	scanf("%d%d",&n,&m);
	for(int i=0; i<m; i++)
	{
		scanf("%d%d",&x,&y);
		if(!(cati[x]&7))
			a[x]=(int*)realloc(a[x],(cati[x]+10)*sizeof(int));
		cati[x]++;
		a[x][cati[x]]=y;

		if(!(cati[y]&7))
			a[y]=(int*)realloc(a[y],(cati[y]+10)*sizeof(int));
		cati[y]++;
		a[y][cati[y]]=x;
	}
}
void dfs(int nod)
{
	ok[nod]=true;
	for(int i=1; i<=cati[nod]; i++)
	{
		if(!ok[a[nod][i]])
			dfs(a[nod][i]);
	}
}
int main()
{
	freopen("dfs.in","r",stdin);
	freopen("dfs.out","w",stdout);
	citire();
	for(int i=1; i<=n; i++)
	{
		if(!ok[i])
		{
			rez++;
			dfs(i);
		}
	}
	printf("%d\n",rez);
	return 0;
}