#include<fstream.h>
#define NM 100001

ifstream fin("dfs.in");
ofstream fout("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;
fin>>n>>m;
for(i=0;i<m;i++){ fin>>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);
		}
fout<<cc;
return 0;
}