#include<iostream>
#include<cstdio>
#include<cctype>
#include<set>
#define maxn 50001
#define gys mylove
using namespace std;
int m,n,u,v;
int fa[maxn];
set<int> s;
inline void in(int &x)
{
    x=0;int f=1;char t=getchar();
    while(!isdigit(t)){if(t=='-')f=-1;t=getchar();}
    while(isdigit(t)){x=x*10+t-48;t=getchar();}
    x*=f;
}
inline int uf(int x){
	return fa[x]==x? x:uf(fa[x]);
}
inline void work(){
	in(n);in(m);
	for(int i=1;i<=n;i++) fa[i]=i;
	for(int i=1;i<=m;i++){
		in(u);in(v);
		if(uf(u)!=uf(v)){
			fa[u]=fa[v]=min(uf(u),uf(v));
		}
	}
	for(int i=1;i<=n;i++){
		if(s.find(fa[i])==s.end()) s.insert(fa[i]);
	}
	printf("%d",s.size());
}
inline int Main(){
	freopen("religion.in","r",stdin);
	freopen("religion.out","w",stdout);
	work();
	return 0;
}
int main(){;}
int gys=Main();