#include<fstream.h>
#define  NM 100001
ifstream in("dfs.in");
ofstream out("dfs.out");

struct nod{
 int nr;
 nod *next;
 };
nod *l[NM],*urm[NM];
int n,m,viz[NM],cc;

void add(nod *&l,int x){
nod *nn=new(nod);
nn->nr=x;
nn->next=l;
l=nn;
}

void build(){
int i,x,y;
in>>n>>m;
for(i=0;i<m;i++){
    in>>x>>y;
    add(l[x],y);
    add(l[y],x);
    }
}

void df(int x){
int y;
nod *nc=urm[x];
while(nc){viz[x]=cc;
	  y=nc->nr;
	  nc=nc->next;
	  if(!viz[y]) df(y);
	  urm[x]=nc;
	  }
}

int main(){
int i;
build();
for(i=1;i<=n;i++)  urm[i]=l[i];
for(i=1;i<=n;i++)
  if(!viz[i]){cc++;
	      df(i);
	      }
out<<cc;
return 0;
}