#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

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

int N,M,insule=0;

int const NLIM = 100005;
vector <int> Muchii[NLIM];

bool vizitat[NLIM];

queue <int> Coada;

void DFS(int Nod)
{
    vizitat[Nod]=true;
    for(unsigned int i=0;i<Muchii[Nod].size();i++)
    {
        int Vecin=Muchii[Nod][i];
        if(!vizitat[Vecin])
            DFS(Vecin);
    }
}

void Citire()
{
    fin>>N>>M;
    for(int i=1;i<=N;i++)
    {
        int x,y;
        fin>>x>>y;
        Muchii[x].push_back(y);
        Muchii[y].push_back(x);
    }
    for(int i=1;i<=N;i++)
    {
        if(!vizitat[i])
            insule+=1;
        DFS(i);
    }
}

int main()
{
    Citire();
    fout<<insule<<endl;
    return 0;
}