#include<bits/stdc++.h>
using namespace std;
int n,m,f[500005],a[500005],ans=0,xx,yy;
int find(int x){
	if(f[x] == x) return x;
	return f[x] = find(f[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++) f[i] = i;
	for(int i = 1; i <= m; i++){
		scanf("%d%d",&xx,&yy);
		int fx=find(xx),fy=find(yy);
		if (fx!=fy) f[fx]=fy;
	}
	for(int i = 1; i <= n; i++){
		int w = find(i);
		if(!a[w]){
			ans++;
			a[w]++;
		}
	}
	cout << ans;
	return 0;
}