// Header {{{
// includes {{{
#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
// }}}
using namespace std;
// consts {{{
static const int INF = 1e9;
static const double PI = acos(-1.0);
static const double EPS = 1e-10;
// }}}
// typedefs {{{
typedef long long int LL;
typedef unsigned long long int ULL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<ULL> VULL;
typedef vector<VULL> VVULL;
typedef vector<double> VD;
typedef vector<VD> VVD;
typedef vector<bool> VB;
typedef vector<VB> VVB;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<string> VS;
typedef vector<VS> VVS;
typedef pair<int, int> PII;
typedef complex<int> P;
// }}}
// macros & inline functions {{{
// syntax sugars {{{
#define FOR(i, b, e) for (int i = (b); i < (e); ++i)
#define FORI(i, b, e) for (int i = (b); i <= (e); ++i)
#define RFOR(i, b, e) for (int i = (b); i > (e); --i)
#define RFORI(i, b, e) for (int i = (b); i >= (e); --i)
#define REP(i, n) FOR(i, 0, n)
#define REPI(i, n) FORI(i, 0, n)
#define RREP(i, n) RFOR(i, n, 0)
#define RREPI(i, n) RFORI(i, n, 0)
#define OPOVER(_op, _type) inline bool operator _op (const _type &t) const
// }}}
// conversion {{{
inline int toInt(string s) {
    int v; istringstream sin(s); sin >> v; return v;
}
template<class T> inline string toString(T x) {
    ostringstream sout; sout << x; return sout.str();
}
// }}}
// array and STL {{{
#define ARRSIZE(a) ( sizeof(a) / sizeof(a[0]) )
#define F first
#define S second
#define MP(a, b) make_pair(a, b)
#define PB(e) push_back(e)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EXIST(s, e) ((s).find(e) != (s).end())
// }}}
// for readable code {{{
#define EVEN(n) (n % 2 == 0)
#define ODD(n) (!EVEN(n))
// }}}
// string manipulation {{{
inline VS split(string s, char delimiter) {
    VS v; string t; REP(i, s.length()) {
        if (s[i] == delimiter) v.PB(t), t = ""; else t += s[i];
    } v.PB(t); return v;
}
inline string join(VS s, string j) {
    string t; REP(i, s.size()) {
        t += s[i] + j;
    } return t;
}
// }}}
// geometry {{{
#define Y real()
#define X imag()
// }}}
// 2 dimentional array {{{
P dydx4[4] = { P(-1, 0), P(0, 1), P(1, 0), P(0, -1) };
P dydx8[8] = { P(-1, 0), P(0, 1), P(1, 0), P(0, -1), P(-1, 1), P(1, 1), P(1, -1), P(-1, -1) };
int g_height, g_width;
bool in_field(P p) {
    return (0 <= p.Y && p.Y < g_height) && (0 <= p.X && p.X < g_width);
}
// }}}
// }}}

#define PRINT(s) sout << (s) << endl
int itemNum[11];
int n, tmp, powerup, rem;

int main(int argc, char** argv) {
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    cin >> n;
    REP(i, 3 * n){
    	cin >> tmp;
    	itemNum[tmp]++;
    }
    
    powerup = 0;
    rem = 0;
    FORI(i, 1, 10){
    	powerup += itemNum[i] / 2;
    	rem += itemNum[i] % 2;
    }
    
    powerup += rem / 4;

	cout << powerup << endl;

    return 0;
}