#include <bits/stdc++.h>
//#include <atcoder/all>
//using namespace atcoder;
//using mint = modint998244353;
using namespace std;
using ll= long long;
using ull=unsigned long long;
using ldo =long double;
#define rep(i,n,k) for(ll i = k; i < (ll)(n); i++)
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll INF = 1e18;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;

int main(){
    ll N,A,ans=0;
    cin>>N;
    map<ll,ll> z;
    rep(i,N,0){
        cin>>A;
        z[A]++;
    }
    for(auto [x,y]:z){
        if(y>=2){
            ans+=y/2;
        }
    }
    cout<<ans<<endl;
}