#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N;
  cin>>N;
  vector<int> S(11);
  for(int i=0;i<3*N;i++){
      int x;
      cin>>x;
      S[x]++;
  }
  int ans = 0;
  int sum = 3*N;
  for(int i=0;i<11;i++){
      ans += S[i]/2;
      sum -= (S[i]/2)*2;
      S[i] %= 2;
  }
  cout<<ans+sum/4<<endl;
}