#include <iostream>
#include <fstream>
#define Nmax 200001
using namespace std;

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

struct nod
{
    int x;
    nod *urm;
}*v[Nmax];

int n,m,viz[Nmax],k;

void add(nod *&prim,int val)
{
    nod *p; p=new nod;
    p->x=val;
    p->urm=prim;
    prim=p;
}

void citire()
{
    fin>>n>>m;
    int x,y;
    for(int i=1;i<=n;++i)
    {
        fin>>x>>y;
        add(v[x],y);
        add(v[y],x);
    }
}

void DFS(int varf)
{
    nod *p;
    viz[varf]=1;
    for(p=v[varf];p;p=p->urm)
        if(viz[p->x]==0)
            DFS(p->x);
}


int main()
{
    citire();
    for(int i=1;i<=n;++i)
        if(viz[i]==0)
        {
            DFS(i);
            k++;
        }
    fout<<k;
    return 0;
}