//#define EPS 0.01
#include <math.h>   
#include <fstream>   
using namespace std;   
int n;   
float x[1015],y[1015];
void citire(){   
ifstream fin("patrate3.in");   
fin>>n;   
for (int i=0;i<n;i++)   
   fin>>x[i]>>y[i];   
fin.close();   
}   
void bule(){   
int ok=1,p=n;   
while(ok){   
ok=0;   
p--;   
for (int i=0;i<p;i++)   
   if (x[i]>x[i+1]){   
   float aux=x[i];
   x[i]=x[i+1];   
   x[i+1]=aux;   
   aux=y[i];   
   y[i]=y[i+1];   
   y[i+1]=aux;   
   ok=1;   
   }   
}   
}   
  
int da(float a,float b,int m){
if (fabs(x[m]-a)==0 && fabs(y[m]-b)==0)
  return 1;   
return 0;   
}   
  
int binar(float a,float b,int p,int u){
if (p>u)   
  return 0;   
int m=(p+u)/2;   
if  (da(a,b,m))   
     return 1;   
if (x[m]<a)   
    return binar(a,b,m+1,u);   
return binar(a,b,p,m-1);   
}   
  
long numarare(){   
long nr=0;   
for (int i=0;i<n-1;i++)   
   for (int j=i+1;j<n;j++){   
      if (binar(x[j]+(y[i]-y[j]),y[j]+(x[j]-x[i]),i,n)==1)   
    if (binar(x[i]+(y[i]-y[j]),y[i]+(x[j]-x[i]),i,n)==1){   
       nr++;   
       break;}   
   }   
return nr;   
}   
int main(){   
citire();   
bule();   
ofstream fout("patrate3.out");   
fout<<numarare()<<"\n";   
fout.close();   
return 0;   
}