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

ifstream in("dfs.in");
ofstream out("dfs.out");

const int N=100001;
vector<int> a[N];
bool conf[N];
int cont;

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

void nr_comp(size_t x)
{
	size_t y;
	for(size_t i=0;i<a[x].size();i++)
	{
		y=a[x][i];
		if(!conf[y])
		{
			conf[y]=1;
			cont++;
			nr_comp(y);
		}
	}
}

int main()
{
	citire();
	nr_comp(1);
	out<<cont;
	
	in.close();
	out.close();
	
	return 0;
}