package timus;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
/**
* Created by sherxon on 12/6/16.
*/
public class FlatSpots1617 {
public static void main(String[] args) {
Scanner in =new Scanner(System.in);
int n=in.nextInt();
Map<Integer, Integer> map=new HashMap<>();
for (int i = 0; i < n; i++) {
int k=in.nextInt();
if (!map.containsKey(k))
map.put(k, 1);
else map.put(k, map.get(k)+1);
}
System.out.println(map.values().stream().filter(s->s/4>0).
reduce(0, (a,b)->a+b/4).intValue());
}
}