#include <iostream>
#include <fstream>
#include <utility>
#include <algorithm>
#include <set>
#include <vector>
#include <stack>
#include <queue>

using namespace std;

ifstream f("dfs.in");
ofstream g("dfs.out");

int **A, *Viz;
int nr, n , m;

void df(int start, int **A, int *&Viz){
	int i, x, *viz = new int [n+1];
	stack <int> S;
	for(i=0; i<=n ;i++){
		viz[i] = 0;
	}
	S.push(start);
	while(!S.empty()){
		x = S.top();
		S.pop();
		if(!viz[x]){
			viz[x] = 1;
			Viz[x] = 1;
			for(i=n; i>=1; i--){
				if(A[x][i] && !viz[i]){
					S.push(i);
				}
			}
		}
	}
}

int main (){
	int x, y, i, j, nod = 1;

	f>>n;
	f>>m;

	Viz = new int [n+1];
	for(i=0; i<=n ;i++){
		Viz[i] = 0;
	}
	A = new int * [n+1];
	for(i=1; i<=n; i++){
		A[i] = new int [n+1];
	}

	for(i=1; i<=m ;i++){
		f>>x>>y;
		A[x][y] = A[y][x] = 1;
	}

	nod = 1;
	while(nod <= n){
		if(!Viz[nod]){
			df(nod, A, Viz);
			nr = nr + 1;
		}
		nod = nod + 1;
	}

	g<<nr;
	return 0;
}