#include <cstdlib>
#include <cstdio>
using namespace std;
const int MAXN=100010;
int num[MAXN],x,y,ans=0;

int find(int k) {return ((k==num[k])?k:(num[k]=find(num[k])));}
inline void merge(int x,int y){num[y]=x;}

int main()
{
	freopen("explosion.in","r",stdin);
	freopen("explosion.out","w",stdout);
	scanf("%d",&x);
	for(int i=1;i<=100001;i++) num[i]=i;
	while(x!=-1)
	{
		scanf("%d\n",&y);
		x=find(x);y=find(y);
		if(x==y) ans++;
		else merge(x,y);
		scanf("%d\n",&x);
	}
	printf("%d\n",ans);
	return 0;
}