#include<stdio.h>
int viz[100100],muchie1[200100],muchie2[200100],conex;
int *lista[100100];
void df(int i){
	int j;
	viz[i]=1;
	for(j=1;j<=lista[i][0];++j){
		if(!viz[lista[i][j]]){
			df(lista[i][j]);
		}
	}
}
int main(){
	freopen("dfs.in","r",stdin);
	freopen("dfs.out","w",stdout);
	int n,m,i;
	scanf("%d%d",&n,&m);
	for(i=0;i<m;++i){
		scanf("%d%d",&muchie1[i],&muchie2[i]);
		++viz[muchie1[i]];
		++viz[muchie2[i]];
	}
	for(i=1;i<=n;++i){
		lista[i]=new int (viz[i]+1);
		lista[i][0]=0;
		viz[i]=0;
	}
	for(i=0;i<m;++i){
		lista[muchie1[i]][++lista[muchie1[i]][0]]=muchie2[i];
		lista[muchie2[i]][++lista[muchie2[i]][0]]=muchie1[i];
	}
	
	for(i=1;i<=n;++i){
		if(!viz[i]){
			++conex;
			df(i);
		}
	}
	printf("%d\n",conex);
	
	fclose(stdin);
	fclose(stdout);
	return 0;
}