#include<fstream.h>
#include<math.h>

struct tri
{
	float x,y,l;
	
};
tri a[1501],aux;
int n,i,j,nr;
int main()
{
	ifstream f("triang.in");
	ofstream g("triang.out");
	f>>n;
	for(i=1;i<=n;i++)
		f>>a[i].x>>a[i].y;
	for(i=1;i<n;i++)
		for(j=i+1;j<=n;j++)
			if(a[i].x>a[j].x)
			{
				aux=a[i];
				a[i]=a[j];
				a[j]=aux;
			}
			for(i=1;i<=n;i++)
			a[i].l=abs(sqrt((a[i+1].x-a[i].x)*(a[i+1].x-a[i].x)+(a[i+1].y-a[i].y)*(a[i+1].y-a[i].y)));	
	
	//for(i=1;i<=n;i++)
		//g<<a[i].l<<" ";
	for(i=1;i<=n-1;i++)
		for(int j=i+1;j<=n;j++)
		if(a[i].l==a[j].l)
			nr++;
		//g<<"\n";
		g<<nr;
	return 0;
}