#include<fstream>
using namespace std;
ifstream in("dfs.in");
ofstream out("dfs.out");

int n,m,a[2000][2000],v[2000],cc=0;

void citire(){
	int x,y,i;
	in>>n>>m;
	for(i=1; i<=m; i++){
		in>>x>>y;
		a[x][y]=a[y][x]=1;
	}
}

void bf(int start){
	v[start]=cc;
	for(int i=1; i<=n; i++)
		if(a[start][i] and !v[i])
			bf(i);
}

int main(){
	citire();
	for(int i=1; i<=n; i++)
		if(!v[i]){
			cc++;
			bf(i);
		}
	out<<cc;
	return 0;
}