#include <cstdlib>
#include <iostream>
/*#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
*/#define rep(i,n) for (int i=0;i<(n);i++)
#define debug(x) cout<<#x<<": "<<x<<endl

using namespace std;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int N, tmp, a[11] = {0}, sum = 0, cnt = 0;
    cin >> N;
    
    rep(i, 3 * N){
           cin >> tmp;       
           a[tmp]++;
    }
    
    for(int i = 1; i < 11; i++){
           while(a[i] > 1){
                      a[i] -= 2;
                      cnt++;
           }
           sum += a[i];       
    }
    
    cout << cnt + sum / 4 << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}