#include<cstdio>
#include<algorithm>
#include<math.h>
using namespace std;
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("triang.in","r",stdin);
freopen("triang.out","w",stdout);
scanf("%d",&n);
for(i=1;i<=n;i++)
      scanf("%lf%lf",&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);
return 0;}