text: #include <bits/stdc++.h>
  
  #define FI(i,a,b) for(int i=(a);i<=(b);i++)
  #define FD(i,a,b) for(int i=(a);i>=(b);i--)
  
  #define LL long long
  #define Ldouble long double
  #define PI 3.1415926535897932384626
  
  #define PII pair<int,int>
  #define PLL pair<LL,LL>
  #define mp make_pair
  #define fi first
  #define se second
  
  using namespace std;
  
  int n, c[105], x;
  
  int main(){
  	scanf("%d", &n);
  	FI(i, 1, n){
  		scanf("%d", &x);
  		c[x]++;
  	}
  	
  	int ans = 0;
  	
  	FI(i, 1, 100) ans += c[i] / 2;
  	printf("%d\n", ans);
  	return 0;
  }
  