#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MAXN 500010
inline ll read(){
    ll x=0,f=1;
    char c=getchar();
    while(c<'0'||c>'9'){
        if(c=='-')f=-1;
        c=getchar();
    }
    while(c>='0'&&c<='9'){
        x=x*10+c-'0';
        c=getchar();
    }
    return x*f;
}
std::map <int,int> mp;
ll f[MAXN];
ll n,m,ans;
ll find(ll x){
    if(f[x]==x)return x;
    else return f[x]=find(f[x]);
}
int main(){
    freopen("religion.in","r",stdin);
    freopen("religion.out","w",stdout);
    n=read(),m=read();
    for(int i=1;i<=n;i++)f[i]=i;
    for(int i=1;i<=m;i++){
        ll l=read(),r=read();
        f[find(l)]=f[find(r)];
    }
    for(int i=1;i<=n;i++){
        if(!mp[find(i)]){
            ans++;
            mp[find(i)]=1;
        }
    }
    cout<<ans;
    return 0;
}