#include <bits/stdc++.h> 
using namespace std;
#include <ios>
#include <iomanip>
#include <iostream>
#include <string>
#include <algorithm>

int main(){
  int a;
  int count3=0;
  int count2=0;
  cin >>a;
  a *=3;
  vector<int> vec(a);
  for(int i=0;i<a;i++){
    cin >> vec.at(i);
  }
  for(int k=0;k<11;k++){
    int count1=0;
      for(int i=0;i<a;i++){
    	if(k==vec.at(i)){
          count1 ++;
        }
      }
    count2=count2+count1 /2;
    count3=count3+count1 %2;
  }
  cout << count2+count3/4;
}