#include <vector>
#include <iostream>
using namespace std;

int main()
  {
   unsigned K;
   while(cin>>K)
     {
      vector<unsigned> tab(K);
      for(unsigned k=0;k<K;++k) cin>>tab[k];
      unsigned para=0; 
      for(unsigned i=0;i<K;++i) for(unsigned k=i+1;k<K;++k) para+=(tab[i]==tab[k]);
      cout<<para<<endl;
     }
   return 0;
  }