#include <bits/stdc++.h>
using namespace std;

const int N = 50010;

int p[N],n,m,ans,r[N];

int fd(int x){
	if(p[x]!=x){
		p[x]=fd(p[x]);
	}
	return p[x];
}

int main(){
	freopen("religion.in","r",stdin);
	freopen("religion.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)p[i]=i;
	for(int i=1;i<=m;i++){
		int x,y;
		scanf("%d%d",&x,&y);
		if(fd(x)!=fd(y)){
			p[fd(x)]=fd(y);
		} 
	}
	for(int i=1;i<=n;i++){
		fd(i);
		r[p[i]]++;
	}
	for(int i=1;i<=n;i++)if(r[i])ans++;
	printf("%d",ans);
	return 0;
}