#include<stdio.h>
#include<vector>
using namespace std;

int n,m,i,v[100005],lg[100005],x,y,j,nr;
vector <int> a[100005];

void dfs(int nod){
	int i;
	v[nod]=1;
	for(i=0;i<lg[nod];i++)
		if(v[a[nod][i]]!=1)
			dfs(a[nod][i]);
}

int main(){
	FILE*f=fopen("dfs.in","r");
	FILE*g=fopen("dfs.out","w");
	
	fscanf(f,"%d %d",&n,&m);
	for(i=1;i<=m;i++){
		fscanf(f,"%d %d",&x,&y);
		a[y].push_back(x);
		a[x].push_back(y);
	}
	
	for(i=1;i<=n;i++)
		lg[i]=a[i].size();
	
	for(i=1;i<=n;i++){
		if(v[i]!=1){
			nr++;
			dfs(i);
		}
	}
	
	fprintf(g,"%d",nr);
	
	fclose(f);
	fclose(g);
	return 0;
}