/*
TASK: tri
LANG: C++
*/
#include<iostream>
using namespace std;
 long hora[600][600];
 long a,b;
 long n,i,j,br=0,br1=0,k,i1,j1,a1,a2,a3;
int main()
{
 // Dano da raboti :)

 cin>>n;


 for(i=1;;i++)
 {
  cin>>a;   cin>>b;
 
  if(a==0 && b==0) break;
 
  else
  {
   hora[a][b]=1;
   hora[b][a]=1;
  }

 }
 
 for(i=1;i<=n;i++)
 {//glaven for
  for(j=1;j<=n;j++)
  {//for
  // NB!! i e 4oveka, a j e poznaiq mu  
   if(hora[i][j]==1)
   {//if
    for(j1=1;j1<=n;j1++)
    {//for
    if(hora[j][j1]==1 && hora[i][j1]==1 && i!=j1 && j1!=j) {/*cout<<i<<" poznava "<<j<<" poznava "<<j1<<endl;*/ br++;}
    }//for         
  }//if
 }//for
}// glaven for
    
    if(br%4==0) {br=br/4; br--; if(br!=-1) cout<<br; else cout<<"0"; cout<<"\n"; return 0;}
    if(br%4!=0) {br=br/4; if(br!=-1) cout<<br; else cout<<"0"; cout<<"\n"; return 0;}
return 0;
}
