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

const int N=1e5;
ifstream f("dfs.in");
ofstream g("dfs.out");
vector <int> graf[N+1];
bitset <N+1> viz;
int m,n;
void DFS(int x)
{
	viz[x]=1;
	for(auto i:graf[x])
		if(viz[i]==0)
		DFS(i);
}

int main()
{
	int x,y,nrc=0;
	f>>n>>m;
	for(int i=1; i<=m; i++)
	{
		f>>x>>y;
		graf[x].push_back(y);
		graf[y].push_back(x);
	}
	DFS(1);
	nrc++;
	for(int i=1; i<=n; i++)
	{
		if(viz[i]==0)
		{
			DFS(i);
			nrc++;
		}
	}
	g<<nrc<<endl;
	f.close();
	g.close();
}