#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;

#define in "dfs.in"
#define out "dfs.out"
#define N 100005

vector <bool> d(N+1, false);
vector <int> LIST[N];
int n, m, sol = 0;

void DFS (int x)
{
	d[x] = 1;
	for (unsigned i = 0; i < LIST[x].size(); ++i)
		if (!d[LIST[x][i]])
			DFS (LIST[x][i]);			
}

int main ()
{
	ifstream fin (in);
	fin >> n >> m;
	for (int i = 0; i < m; ++i) {
		int x, y;
		fin >> x >> y;
		LIST[x].push_back (y);
		LIST[y].push_back (x);
	}
	fin.close();
	for (int i = 1; i <= n; ++i)
		sort (LIST[i].begin(), LIST[i].end());
	for (int x = 1; x <= n; ++x)
		if (!d[x])
			sol++, DFS (x);
	ofstream fout (out);
	fout << sol;
	fout.close();
	return 0;
}