#include <fstream>
#include <vector>
const int MAX = 100100;

using namespace std;

ifstream fin ("dfs.in");
ofstream fout("dfs.out");
vector <int> gr[MAX];
int uz[MAX],facut,sol;
void dfs(int nod);
int main()
{
    int n,m;
    fin>>n>>m;
    for(int i=1;i<=m;++i){
        int x,y;
        fin>>x>>y;
        gr[x].push_back(y);
        gr[y].push_back(x);
    }
    for(int i=1;i<=n;++i){
        facut=0;
        dfs(i);
        sol+=facut;
    }
    fout<<sol<<'\n';
    return 0;
}
void dfs(int nod)
{
    if(!uz[nod]){
        facut=1;
        uz[nod]=1;
        for(int i=0;i<(int)gr[nod].size();++i)uz[gr[nod][i]]=1;
    }
}