#include <iostream>
#include <fstream>
#define nmax 100000
using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
int n,m,viz[nmax+5];
struct nod
{
    int info;
    nod *urm;
}*v[nmax+5],*c,*d,*gg;
void dfs(int k)
{
    viz[k]=1;nod *e;
    e=v[k];
    while(e->urm)
    {
        e=e->urm;
        if(!viz[e->info])
        dfs(e->info);
    }
}
int main()
{
    int x,y,s=0,maxv=0;
    fin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        v[i]=new nod;
        v[i]->info=i;
        v[i]->urm=0;
    }
    while(fin>>x>>y)
    {
        c=v[x];
        while(c->urm)
            c=c->urm;
        d=new nod;
        d->urm=0;
        d->info=y;
        c->urm=d;
        c=v[y];
        while(c->urm)
            c=c->urm;
        d=new nod;
        d->urm=0;
        d->info=x;
        c->urm=d;
    }
    for(int i=1;i<=n;i++)
    {
        if(!viz[i])
            {s++;dfs(i);}
    }
    fout<<s;
    fin.close();
    fout.close();
    return 0;
}