#include<iostream>
#include<fstream>
#include<vector>

using namespace std;

void dfs(vector< vector<int> > v, vector<int>& viz, int nod)
{
	viz[nod] = 1;
	for (int i = 0; i < v[nod].size(); i++)
		if (viz[v[nod][i]] != 1)
			dfs(v, viz, v[nod][i]);
}

int main()
{
	int n, m, i, j, nod1, nod2, k = 0;
	ifstream f("dfs.in");
	f >> n >> m;
	vector< vector<int> > v(n+1);
	vector<int>viz(n + 1, 0);
	for (i = 0; i < m; i++)
	{
		f >> nod1 >> nod2;
		v[nod1].insert(v[nod1].begin(), nod2);
		v[nod2].insert(v[nod2].begin(), nod1);
	}
	for (i = 1; i <= n; i++)
		if (!v[i].size())
			v[i].insert(v[i].begin(), 0);
	for (i = 1; i <= n; i++)
	{
		for (j = 0; j < v[i].size(); j++)
		{
			if (!viz[i])
			{
				k++;
				dfs(v, viz, v[i][j]);
			}
		}
	}
	ofstream g("dfs.out");
	g << k;
	f.close();
	return 0;
}