#include<fstream>
using namespace std;
long n,m, vizitat[100005],nrc;
typedef struct nod
{
        int info;
        nod* urm;
        
        
        } * tnod;
tnod v[100005];
void citire()
{
     int i,j,x,y;
     ifstream f ("dfs.in");
     f>>n>>m;
     tnod p;
     for (i=1;i<=n;i++)
{
     f>>x>>y;
     p=new nod;
     p-> info=x;
     p-> urm = v[y];
     v[y]=p;
     p= new nod;
      p-> info= y;
      p-> urm= v[x];
      v[x]=p;
      }
      f.close();
      }
      void df(int nod)
      {
           tnod p;
           vizitat [nod]=1;
           for (p=v[nod]; p!= NULL; p=p-> urm )
           if (!vizitat[p->info])
           df (p->info);
           }
void afisare()
{
     ofstream g ("dfs.out");
     g<<nrc;
     g.close();
 }
 
 int main()
 {
     int j,ok=1,k;
     citire();
     for(k=1;k<=n;k++)
     if (vizitat[k]==0)
     {nrc ++;
     df(k);
                       }
                       afisare();
                       return 0;
     }