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

int x,a[105],maxn,ans;
int main(){
    int n;
    cin >> n;
    for(int i = 1; i <= n; i++){
        cin >> x;
        a[x]++;
        if(x>maxn)maxn = x;
    }
    for(int i = 1; i <= maxn; i++){
        if(a[i]>=2)ans+=a[i]/2;
    }
    cout << ans/2;
    return 0;
}