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

namespace
{
int A[ 20 ];
}

int main()
{
int i;
int x;
int N;
int iSum;
int iChk;

	cin >> N;

	N *= 3;
	for( i = 0; i < N; i++ )
	{
		cin >> x;
		A[ x ]++;
	}

	iSum = 0;
	iChk = 0;
	for( i = 1; i <= 10; i++ )
	{
		iSum += A[ i ] / 2;
		A[ i ] %= 2;
		if( A[ i ] % 2 > 0 ) iChk++;
	}

	iSum += iChk / 4;

	cout << iSum << endl;

	return 0;
}