#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

int main()
{
    int n;
    cin >> n;

    bitset<32> bs;
    int ret = 0;
    for(int i=0; i<3*n; ++i){
        int a;
        cin >> a;
        if(bs[a])
            ++ ret;
        bs[a] = !bs[a];
    }
    ret += bs.count() / 4;
    cout << ret << endl;

    return 0;
}