//
//  main.cpp
//  dfs
//
//  Created by Catalina Brinza on 11/30/13.
//  Copyright (c) 2013 Catalina Brinza. All rights reserved.
//

#include <fstream>
#include <vector>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
vector<vector<int>> a;
vector<bool> v;

void dfs(int x)
{int i=0;
    v[x]=true;

    while (a[x].size()!=0 && i!=a[x].size())
    {if (!v[i]) dfs(i); i++;}
    return;
}



int main()
{
    int n,m,i,x,y;
    f>>n>>m;
  
    for (i=0;i<m;++i)
    {
        f>>x>>y;
        a[x].push_back(x);
        a[y].push_back(y);
    }
    v.push_back(false);
    for (i=1;i<=n;++i)
        v.push_back(false);
    x=0;
    for (i=1;i<=n;++i)
    {
        if (!v[i]) {dfs(i);x++;}
    }
    g<<x;
    return 0;
}