#include <cstdio>
#include <algorithm>

using namespace std;


#define file_in "patrate3.in"
#define file_out "patrate3.out"

#define Nmax 1010
#define f first
#define s second

pair <double, double> p[Nmax];
int i,n,j;
double mijx,mijy,dx,dy,x1,x2,x3,x0,y0,y1,y2,y3,y4;
int nrp;

double abs(double a) { return a>=0?a:-a; }

int bs(double x)
{
	int ls=1;
	int ld=n,mij;
	while(ls<=ld)
	{
		mij=(ls+ld)>>1;
		
		if (p[mij].f==x)
			return 1;
		if (p[mij].f<x)
			ls=mij+1;
		else
			ld=mij-1;
		mij=(ld+ls)>>1;
			
	}
	
	return 0;
}			
	

int main()
{
	freopen(file_in,"r",stdin);
	freopen(file_out,"w",stdout);
	
	scanf("%d", &n);
	for (i=1;i<=n;++i)
          scanf("%lf %lf", &p[i].f, &p[i].s);
	
	sort(p+1,p+n+1);
	
	/*for (i=1;i<=n;++i)
		 printf("%.4lf %.4lf\n", p[i].f, p[i].s);*/
	
	nrp=0;
	for (i=1;i<=n;++i)
		 for (j=i+1;j<=n;++j)
		 {
			 x0=p[i].f;
			 x1=p[j].f;
			 y0=p[i].s;
			 y1=p[j].s;
			 mijx=(x0+x1)/2.0;
			 mijy=(y0+y1)/2.0;
			 dx=abs(mijx-x0);
			 dy=abs(mijy-y0);
			 if (y0<y1)
			 {
				 x2=mijx+dy;
				 y2=mijy-dx;
				 x3=mijx-dy;
				 y3=mijy+dx;
			 }
			 else
			 {
				 x2=mijx-dy;
				 y2=mijy-dx;
				 x3=mijx+dy;
				 y3=mijy+dx;
			 }
			/*// printf("%.4lf %.4lf %.4lf %.4lf %.4lf %.4lf %.4lf %.4lf\n", x0,y0,x1,y1,x2,y2,x3,y3);
			 if (bs(x2) && bs(x3)) */
			 for (int k=1;k<=n;++k)
				  for (int l=1;l<=n;++l) 
				      if ((p[k].f==x2 && p[k].s==y2 && p[l].f==x3 && p[l].s==y3) ||(p[l].f==x2 && p[l].s==y2 && p[k].f==x3 && p[k].s==y3) )	{
						  nrp++;
						  //printf("%.4lf %.4lf %.4lf %.4lf %.4lf %.4lf %.4lf %.4lf\n", x0,y0,x1,y1,x2,y2,x3,y3);
					  }
				      //printf("DA\n");
		 }
 
			 
			 
	printf("%d\n", nrp);		 
			 
			 
	
	fclose(stdin);
	fclose(stdout);
	
	return 0;
	
}