#include<cstdio>
#include<vector>
using namespace std;
int nr,p,u,x1,y1,n,m,i,d[100002],x[100002];
vector<int> h[100002];
vector<int>::iterator it;
int main()
{
freopen("dfs.in","r",stdin);	
freopen("dfs.out","w",stdout);
scanf("%d",&n);
scanf("%d",&m);
for(i=1;i<=n;i++)
{
	scanf("%d",&x1);
	scanf("%d",&y1);
	h[x1].push_back(y1);
	h[y1].push_back(x1);
}
for(i=1;i<=n;i++)
if(d[i]==0)
{
	d[i]=1;
	x[1]=i;
	p=1;
	u=1;
	nr++;
	while(p<=u)
	{
		for(it=h[x[p]].begin();it!=h[x[p]].end();it++)
			if(d[*it]==0)
			{
				u++;
				x[u]=*it;
				d[*it]=1;
			}
		p++;
	}
}
printf("%d\n",nr);
return 0;
}