text: #include <map>
  #include <set>
  #include <list>
  #include <cmath>
  #include <ctime>
  #include <deque>
  #include <queue>
  #include <stack>
  #include <string>
  #include <bitset>
  #include <cstdio>
  #include <limits>
  #include <vector>
  #include <climits>
  #include <cstring>
  #include <cstdlib>
  #include <fstream>
  #include <numeric>
  #include <sstream>
  #include <iostream>
  #include <algorithm>
  #include <unordered_map>
  
  using namespace std;
  
  
  int main(){
      int n, i, j, countt = 0;
      cin >> n;
      vector<int> c(n);
  
      for(int c_i = 0;c_i < n;c_i++){
         cin >> c[c_i];
      }
  
      map<int, int> num;
  
      for(i = 0; i < n; i++){
          num[c[i]]++;
      }
  
      for(map<int, int>::iterator it = num.begin(); it != num.end(); it++){
           //cout << it->first << " => " << it->second << endl;
              countt = countt + it->second/2;
      }
  
      cout << countt << endl;
  
      return 0;
  }
  