#include <fstream>
#include <algorithm>
#include<cstdio>
#include<math.h>
using namespace std;
ifstream f("transport.in");
ofstream g("transport.out");

/*int main()
{

    return 0;
}*/

struct P
{
    double x,y;
};
P a[1501];
int i,n,j;
double r;
long long k;

int C(P a,P b)
{
    return a.x<b.x||(a.x==b.x&&a.y<b.y);
}

int bin(int p,int q,double c,double d)
{
    int m = (p+q)/2;
    if( p > q)
          return 0;
    if( fabs(c-a[m].x) <0.001 && fabs(d-a[m].y) < 0.001 )
          return m;
    if( a[m].x < c )
          return bin(m+1,q,c,d);
    return bin(p,m-1,c,d);
}

int main()
{
    //freopen("transport.in","r",stdin);
    //freopen("transport.out","w",stdout);

    //scanf("%d",&n);
    f >> n;
    for(i=1;i<=n;i++)
         // scanf("%lf%lf",&a[i].x,&a[i].y);
        f >> a[i].x >> a[i].y;
    sort( a+1 , a+n+1 , C);
    r = sqrt(3);
    for( i = 1 ; i < n-1 ; i++ )
    for( j = i+1 ; j < n ; j++ )
      {
          if( bin( j+1 , n , (a[i].x+a[j].x)/2+r*(a[i].y-a[j].y)/2 , (a[i].y+a[j].y)/2+r*(a[j].x-a[i].x)/2))
             k++;
          if( bin( j+1 , n , (a[i].x+a[j].x)/2+r*(a[j].y-a[i].y)/2 , (a[i].y+a[j].y)/2+r*(a[i].x-a[j].x)/2))
             k++;
      }
        //printf("%lld",k);
        g << k+1;
    return 0;
}