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