#include<fstream>
#include <stdio.h>
#include <math.h>
using namespace std;

ifstream f("patrate3.in");
ofstream g("patrate3.out");

int n,i,j,nrc,verif,nrsquare;
int mijx,mijy,dx,dy;

long x[1001],y[1001];
char buff[40];
int xa,xb,ya,yb,xplan1,xplan2,yplan1,yplan2;

void sortare_y()
{int change=1,aux;
 while(change==1)
   {change=0;
    for(i=1; i<=n-1; i++)
       if((y[i]>y[i+1])||(y[i]==y[i+1] && x[i]>x[i+1]))
         {change=1;
          aux=y[i];
          y[i]=y[i+1];
          y[i+1]=aux;
          aux=x[i];
          x[i]=x[i+1];
          x[i+1]=aux;}
  }       
}

void search(int a, int b)
{int end,begin,mij,gasit;
 gasit=0;
 begin=1; end=n;  
 while(begin<end)
  {mij=(end+begin)/2;
   if(x[mij]==a && y[mij]==b)
      {gasit=1; break;}
   if(y[mij]<b)
      begin=mij+1;
   else
      end=mij-1;}
 if(gasit==1 || (x[end]==a && y[end]==b))
    verif++;     
}

int get_number()
{long nr=0;
int ng=1;
if(buff[nrc]=='-')
  {ng=-1; nrc++;}
while(buff[nrc]>='0' && buff[nrc]<='9')
  {nr=nr*10+buff[nrc]-'0';
   nrc++;
   if(buff[nrc]=='.')
      nrc++;}
nr*=ng;
nr*=10;      
return nr;            
}

int main()
{f>>n;
f.getline(buff,40);
for(i=1; i<=n; i++)
{f.getline(buff,40);
 nrc=0;
 x[i]=get_number();
 nrc++;
 y[i]=get_number();}

sortare_y(); 

nrsquare=0;
for(i=1; i<=n; i++)
  for(j=i+1; j<=n; j++)
  {
     xa=x[j];   ya=y[j];  
     xb=x[i];   yb=y[i]; 
     
     mijx=(xa+xb)/2;
     mijy=(ya+yb)/2;
     dx=fabs(mijx-xa);
     dy=fabs(mijy-ya);
     
     xplan1=mijx+dy; 
     yplan1=mijy-dx;
     xplan2=mijx-dy; 
     yplan2=mijy+dx; 
    
     
     verif=0;  
     search(xplan1,yplan1); 
     search(xplan2,yplan2);
     if(verif==2)
       {nrsquare++;
    }     
  }           
g<<nrsquare;   
f.close();
g.close();
return 0;}