#include <iostream>
#include <fstream>
#include <deque>

#define pb push_back
#define pf push_front
#define l 10
// determinarea componentelor conexe ale unui graf;
using namespace std;

void DFS(int n, int nod,int viz[],deque <int> vecini[]){
   deque <int> stiva;
   int i,gasit,x;
   viz[nod] = 1;
   stiva.pf (nod);
   while(!stiva.empty()){

    i = 1 ;gasit = 0; x =stiva.front();

    for( i = 0  ; i < vecini[x].size(); i++){
        if(viz[vecini[x][i]]!=1)                  // cautam un element ce nu a fost vizita
        {                                                  // daca am gasit intrerupe si adaugam in stiva
            viz[vecini[x][i]] = 1;
            gasit = 1;
            break;
        }
    }

    if(gasit){
        stiva.pf (vecini[x][i]);
    }
    else{
        stiva.pop_front();
    }
   }

}

int main()
{
    int n,m,x,y,sol = 0;
    ifstream f("dfs.in",ios::in);
    ofstream g("dfs.out",ios::out);
    f>>n>>m;
    int viz[n+1];
    deque <int> vecini[n+1] ;
    for(int i = 1; i <= m; i++){
        f>>x>>y;
        vecini[x].pf(y);
        vecini[y].pf(x);
    }
    for( int i = 1 ;i <= n; i++)
        viz[i] = 0;
    for( int i = 1 ;i <= n; i++)
        if(viz[i]==0){
            DFS(n,i,viz,vecini);
            sol++;
        }

    g<<sol;
    return 0;
}