#include <stdio.h>
#include <vector>
#define max 100005
using namespace std;

FILE*f=fopen("dfs.in","r");
FILE*g=fopen("dfs.out","w");

int n,m,i,conexe,nod,nod2,viz[max];
unsigned j;
vector<int> mat[max];

void read1(){
	fscanf(f,"%d %d",&n,&m);
	for(i=1;i<=m;i++){
		fscanf(f,"%d %d",&nod,&nod2);
		mat[nod].push_back(nod2);
		mat[nod2].push_back(nod);
	}
}
void dfs(int i){
	viz[i]=1;
	for(j=0;j<mat[i].size();j++){
		if(!mat[i][j]){
			dfs(mat[i][j]);
		}
	}	
}


int main(){
	read1();
	for(i=1;i<=m;i++){
		if(!viz[i]){
			dfs(i);
			conexe++;
		}
	}
	fprintf(g,"%d",conexe);
	fclose(f);
	fclose(g);
	return 0;
}