#include<cstdio>
#include<algorithm>
#include<math.h>
using namespace std;

struct punct {double x,y;};
punct a[1501];
double r;

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

int cauta(int l,int r,double c,double d){
 int mid,pos=0;
   while ( (l<=r)&&(pos==0) ){
     mid=(l+r)/2;
      if(fabs(c-a[mid].x)<0.001&&fabs(d-a[mid].y)<0.001) pos=mid;
      else if(a[mid].x<c) l=mid+1;
      else r=mid-1;
      }
   return(pos);
}

int main(void){
    freopen("triang.in","r",stdin);
    freopen("triang.out","w",stdout);
     int n,i,j,sol=0;
      scanf("%d",&n);
    for(i=1;i<=n;i++) scanf("%lf%lf",&a[i].x,&a[i].y);
      sort(a+1,a+n+1,cmp); r=sqrt(3);
       for(i=1;i<n-1;++i)
         for(j=i+1;j<n;++j) {
           if(cauta(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)) ++sol;
           if(cauta(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)) ++sol;
                             }
      printf("%d\n",sol);
  return 0;
}