#include <bits/stdc++.h>
using namespace std;
int main(){
	int N,index,sum=0,count[10]={0},ans=0;
	scanf("%d",&N);
	for(int i=0;i<3*N;++i){
		scanf("%d",&index);
		ans+=count[index-1];
		sum+=1-2*count[index-1];
		count[index-1]=1-count[index-1];
	}
	printf("%d\n",ans+sum/4);
}