// AlgFund.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

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

using namespace std;

const int NMAX = 100001;
ifstream fin("dfs.in");
ofstream fout("dfs.out");

int dist[NMAX];
int tata[NMAX];
bool viz[NMAX];
vector<int> G[NMAX+1];
int n, m, s, x;
//int Mat[NMAX+1][NMAX+1];
/*
void Citire_Matrice()
{
    fin >> n >> m;
    int x, y;
    for (int i = 0; i < m; ++i)
    {
        fin >> x >> y;
        Mat[x][y] = 1;
        Mat[y][x] = 1;
    }
}
void Afisare_Matrice()
{
    for(int i=1;i<=n;++i){
        for(int j=1;j<=n;++j)
        cout<<Mat[i][j]<<" ";
    cout<<'\n';}
}

*/
void Citire_Lista()
{
    fin >> n >> m;
    int x, y;
    for(int i = 0; i < m; ++i)
    {
        fin >> x >> y;
        G[x].push_back(y);
    }
}



void Afisare_Lista()
{
    for(int i=1; i<=n; ++i)
    {
        cout<<i<<": ";
        for (auto x :G[i])
            cout<<x<<" ";
        cout<<'\n';
    }
}

void bfs(int start)
{
    queue<int> Q;
    viz[start]=1;
    tata[start]=0;
    Q.push(start);

    while(!Q.empty())
    {
        int nod = Q.front();
        Q.pop();
        for(auto x : G[nod])
        {

            if(!viz[x])
            {
                tata[x] = nod;
                Q.push(x);
                viz[x]=1;
            }
        }
    }
}

void Afisare_Dist()
{
    for(int i=1; i<=n; ++i)
    {
        if(i==s)
            fout<<"0 ";
        else
        if (dist[i]==0)
            fout<<"-1 ";
        else
            fout<<dist[i]<<" ";

    }
}

void Afisare_Lant(int nod)
{
    if (tata[nod]==0)
        fout<<nod;
    else
        Afisare_Lant(tata[nod]);
    cout<<nod<<" ";
}

void dfs(int nod)
{
    //cout<<nod<<" ";
    viz[nod]=1;
    for (auto x : G[nod])
        if(!viz[x])
        dfs(x);
}

void Componente_Conexe()
{
    int numar_Componente_Conexe=0;
    for(int i=1;i<=n;++i)
    {
        if(!viz[i])
        {
            dfs(i);
            numar_Componente_Conexe++;
        }
    }
    fout<<numar_Componente_Conexe;
}

int main()
{
    //Citire_Matrice();
    //Afisare_Matrice();
    Citire_Lista();
    //Afisare_Lista();
    //bfs(s);
    //Afisare_Dist();
    //Afisare_Lant(x);
    Componente_Conexe();

    return 0;
}