DSU

#include<bits/stdc++.h>
using namespace std;
typedef long long  ll;
typedef unsigned long long ull;
typedef pair<ll,ll>pll;
typedef pair<ll,pair<ll,ll>>plll;
#define bismillah; (ios_base:: sync_with_stdio(false),cin.tie(NULL));
#define vll(v) v.begin(),v.end()
#define all(x) x.rbegin(),x.rend()
#define min3(a, b, c)   min(a, min(b, c))
#define max3(a, b, c)   max(a, max(b, c))
#define pb push_back
#define eb emplace_back
#define ff first
#define ss second
/// DSU
const int N=1e5+10;
ll p[N+10];
ll sz[N+10];
void make(int v){
 p[v]=v;
 sz[v]=1;
}
int fnd(int v){
  if(v==p[v])return v;
  return p[v]=fnd(p[v]);
}
void Union(int a,int b){
  a=fnd(a);
  b=fnd(b);
  if(a!=b){
    if(sz[a]<sz[b])swap(a,b);
    p[b]=a;
    sz[a]+=sz[b];
  }
}

int main(){
	ll n,m;
	cin>>n>>m;
	for(ll i=1;i<=n;i++)make(i);
	while(m--){
        ll a,b;
        cin>>a>>b;
        Union(a,b);
	}
	ll cnt=0;
	for(ll i=1;i<=n;i++)if(i==p[i])cnt++;
		cout<<cnt<<endl;
}