#include<fstream>
#include<vector>
#include<queue>
#define maxn 100003
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
vector <int> G[maxn],viz(maxn);
int n,m,nr,x1,x2,x;
void adancime(int nod){
    viz[nod]=1;
    while(G[nod].size()){
        if(viz[G[nod].front()]==0){
            x=G[nod].front();
            G[nod].erase(G[nod].begin());
            adancime(x);
        }
        else
            G[nod].erase(G[nod].begin());
    }
}
int main(){
    f>>n>>m;
    for(int i=1;i<=m;++i){
        f>>x1>>x2;
        G[x1].push_back(x2);
        G[x2].push_back(x1);
    }
    for(int i=1;i<=n;++i)
    if(viz[i]==0){
        ++nr;
        adancime(i);
    }
    g<<nr;


}