#include <bits/stdc++.h>
using namespace std;

int main() {
	int N,a,i,up=0,sum=0;
	int p[11]={0};
	cin>>N;
	for(i=0;i<3*N;i++){
		cin>>a;
		p[a]++;
	}
	for(i=1;i<=10;i++){
		up+=(p[i]/2);
		if(p[i]%2)	sum+=1;
	}
	up+=sum/4;
	cout<<up<<endl;
	return 0;
}