#include <fstream>
#include <vector>

using namespace std;

ifstream fin("dfs.in");
ofstream fout("dfs.out");

const int N=100000;

int n,m;
int x,y;
int nr;
vector <int> a[N];
bool viz[N];

void citire()
{
    fin>>n>>m;
    for (int i=0;i<m;i++) {
        fin>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
}

void dfs(int x)
{
    for (int i=0;i<a[x].size();i++) {
        y=a[x][i];
        viz[y]=true;
    }
}

int main()
{
    citire();
    for (int i=1;i<=n;i++) if (!viz[i]) {dfs(i);nr++;}
    fout<<nr;
}