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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int N; cin >> N;
    vector<int> ap(10);
    for(int i=0; i<3*N; i++){
        int a; cin >> a;
        ap.at(a-1)++;
    }
    int bring = 0,answer = 0;
    for(auto a : ap) answer += a/2,bring += a%2;
    answer += bring/4;
    cout << answer << endl;
}