#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=50005;
ll n,m,ans;
ll f[N],b[N];
inline void read(ll &x){
	char c;
	int sum=0,f=1;
	c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-'){
			f=-1;
		}
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		sum=sum*10+c-'0';
		c=getchar();
	}
	x=sum*f;
}
void init(){
	for(int i=1;i<=n;i++){
		f[i]=i;
	}
}
ll find(ll x){
	if(f[x]!=x){
		return f[x]=find(f[x]);
	}
	return x;
}
int main(){
	freopen("religion.in","r",stdin);
	freopen("religion.out","w",stdout);
	read(n),read(m);
	init();
	for(int i=1;i<=m;i++){
		ll x,y;
		read(x),read(y);
		ll fx=find(x);
		ll fy=find(y);
		f[fy]=fx;
	}
	for(int i=1;i<=n;i++){
		find(i);
		if(!b[f[i]]){
			b[f[i]]=1;
			ans++;
		}
	}
	printf("%lld",ans);
	return 0;
}