#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, i, x, y, ans = 0;
cin >> n;
map<int, int> mm;
vector<int> a(n, 0);
for (i = 0; i < n; i++)
{
cin >> a[i];
mm[a[i]]++;
}
for (auto p : mm)
{
y = p.second;
ans += (y / 2);
}
cout << ans << endl;
}
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