#include<cstdio>
#include<vector>
using namespace std;
vector<int> L[1<<17];
bool f[1<<17];
int nrcom,n,m,x,y;
void dfs(int x)
{
	for(vector<int>::iterator it=L[x].begin();it!=L[x].end();it++)
		if(f[*it]==false)
		{
			f[*it]=true;
			dfs(*it);
		}
}
int main()
{
	freopen("dfs.in","r",stdin);
	freopen("dfs.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
	{
		scanf("%d%d",&x,&y);
		L[x].push_back(y);
		L[y].push_back(x);
	}
	for(int i=1;i<=n;i++)
		if(f[i]==false)
		{
			nrcom++;
			f[i]=true;
			dfs(i);
		}
	printf("%d",nrcom);
	return 0;
}