#include<fstream>
#include<vector>
using namespace std;
ifstream in("dfs.in");
ofstream out("dfs.out");
const int N = 100005;
vector<int> G[N];
int n,m,x,y,k;
int v[N];
void proc(int i){
	for(vector<int>::iterator it=G[i].begin() ; it!=G[i].end() ; it++) v[*it]=1;
}
int main(){
	in>>n>>m;
	for(;m;--m){
		in>>x>>y;
		G[x].push_back(y);
		G[y].push_back(x);
	}
	for(int i=1;i<=n;i++){
		if(!v[i]){
			k++;
			proc(i);
		}
	}
	out<<k;
	return 0;
}