#include <cstdio>
const int MAX=50000+10;
int fa[MAX];
inline int find(int x){
	if(fa[x]==x)
		return x;
	return fa[x]=find(fa[x]);
}
inline int read(){
	int x=0;
	char c=getchar();
	while(c<'0'||c>'9')
		c=getchar();
	while(c>='0'&&c<='9'){
		x=x*10+c-'0';
		c=getchar();
	}
	return x;
}
int main(){
	freopen("religion.in","r",stdin);
	freopen("religion.out","w",stdout);
	int n,m;
	n=read(),m=read();
	int x,y;
	int ans=n;
	for(int i=1;i<=n;i++)
		fa[i]=i;
	for(int i=1;i<=m;i++){
		x=read(),y=read();
		int fx=find(x),fy=find(y);
		if(fx!=fy){
			fa[fx]=fy;
			ans--;
			if(ans==1)
				break;
		}
	}
	printf("%d\n",ans);
return 0;
}