#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;
}
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