//Arbore partial de cost minim. Algoritmul Kruskal.
#include <fstream>
using namespace std;

int A[10005][10005], viz[10005];
int n,m;

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

void Read()
{
	f >> n >> m;
	int x,y;
	for(int i=1; i<=m; i++){
		f >> x >> y;
		A[x][y]=A[y][x]=1;
	}
}

void DFS(int i)
{
	viz[i]=1;
	for(int j=1;j<=n;j++){
		if(A[i][j] && !viz[j]){
			DFS(j);
		}
	}
}

int main()
{
	Read();
	int ct=0;
	for(int i=1;i<=n;i++){
		if(!viz[i]){
			ct++;
			DFS(i);
		}
	}
	g << ct;
	return 0;
}