#include<stdio.h>
#include<math.h>

#define NMAX 1500
#define DIF	 0.001

struct pct{ double x,y;};
pct v[NMAX];

void poz(int stg,int dr,int &piv){
int i=stg,j=dr,d=0;
pct aux;
while(i<j){
	if(v[i].x>v[j].x||
	fabs(v[i].x-v[j].x)<0.001&&v[i].y>v[j].y){
		aux=v[i];v[i]=v[j];v[j]=aux;d=1-d;
		}
	i+=d;
	j-=1-d;
	}
piv=i;
}

void qsort(int li,int ls){
int piv;
if(li<ls){
	poz(li,ls,piv);
	qsort(li,piv-1);
	qsort(piv+1,ls);
	}
}

int main(){
freopen("triang.in","r",stdin);
freopen("triang.out","w",stdout);
int i,j,k,n,nrtr=0,up;
double x,y,d1,d1p,dx,dy,r3,r32,
	   dx2,dy2,dxop,dyop,xmin,xmax,ymin,ymax,xx1;
scanf("%d",&n);
r3=sqrt(3);
r32=r3/2;
for(i=0;i<n;i++) {scanf("%lf%lf",&x,&y);v[i].x=x;v[i].y=y;}
qsort(0,n-1);
for(i=0;i<n-2;i++){
	for(j=i+1;j<n-1;j++){
		dx=v[j].x-v[i].x;
		if(v[j].y>=v[i].y) {up=1;dy=v[j].y-v[i].y;}
		else {up=0;dy=v[i].y-v[j].y;}
		if(dy<dx/r3-DIF) continue;
		dxop=dx/2+dy*r32;
		xx1=dx*r32;
		if(up) dyop=dy/2-xx1;
		else dyop=xx1-dy/2;
		xmin=v[i].x+dxop;
		xmax=xmin+DIF;
		xmin=xmin-DIF;
		ymin=v[i].y+dyop;
		ymax=ymin+DIF;
		ymin=ymin-DIF;
		for(k=j+1;k<n&&v[k].x<xmax;k++){
			if(v[k].x<xmin||v[k].y<ymin||v[k].y>ymax) continue;
		 /*	if(v[k].y<ymin||v[k].y>ymax) continue;*/
			nrtr++;
		 /*	printf("%0.4lf %0.4lf ",v[i].x,v[i].y);
			printf("%0.4lf %0.4lf ",v[j].x,v[j].y);
			printf("%0.4lf %0.4lf\n",v[k].x,v[k].y);}*/
			}
		}
	}
printf("%d",nrtr);
return 0;
}