#include <iostream>
#include <fstream>
using namespace std;

int N, M, solution;
int X, Y;
int dad[100100];
bool ap[100100];

inline int find(int X)
{
	int _dad = X;
	while (dad[X] != X) X = dad[X];
	swap(_dad, X);
	while (dad[X] != X)
	{
		int foo = dad[X];
		dad[X] = _dad; 
		X = foo;
	}
	return _dad;
}
inline void join(int X, int Y)
{
	dad[find(X)] = find(Y);
	find(X); find(Y);
}

int main()
{
	ifstream fin("dfs.in");
	fin >> N >> M;
	for (int i = 1; i <= N; i++)
		dad[i] = i;
	for (int i = 1; i <= M; i++)
	{
		fin >> X >> Y;
		join(X, Y);
	}
	for (int i = 1; i <= N; i++)
		ap[find(i)] = true;
	for (int i = 1; i <= N; i++)
		if (ap[i]) solution++;

	ofstream fout("dfs.out");
	fout << solution << '\n';
	fin.close();
	fout.close();
}