#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

vector <int> v[100005];
queue <int> coada;

bool w[100005];
bool wfinal[100005];

void adaugare_coada(int i)
{
    int j,x;

    for(j=0;j<v[i].size();j++)
    {
        x=v[i][j];

        if(w[x]==0)
        coada.push(v[i][j]);
    }


}

int main()
{
    int n,m,i,x,y,j,ct;

    fin>>n>>m;

    for(i=1;i<=m;i++)
    {
        fin>>x>>y;

        v[x].push_back(y);
        v[y].push_back(x);
    }

    for(i=1;i<=n;i++)
    {
        if(w[i]==0)
        {
            wfinal[i]=1;

            coada.push(i);

            while(!coada.empty())
            {
                j=coada.front();
                coada.pop();
                w[j]=1;
                adaugare_coada(j);

            }

        }

    }

    ct=0;

    for(i=1;i<=n;i++)
        if(wfinal[i]==1)
            ct++;

    fout<<ct;





    return 0;
}