#include<stdio.h>
FILE *f=fopen("trapez.in","r"), *g=fopen("trapez.out","w");
struct nod{int x, y;} a[1001];
int n,nr,b[1002001],k,m,i,j,ok,t1,t2;
int main()
{
	fscanf(f,"%d",&n);
	for(i=1;i<=n;i++)
		fscanf(f,"%d %d",&a[i].x,&a[i].y);
	fclose(f);
	for(i=1;i<n;i++)
		for(j=i+1;j<=n;j++) 
			{
			  t1=a[i].y-a[j].y;
			  t2=a[i].x-a[j].x;
			  if(t2==0) b[++m]=t1;
			   else
			     b[++m]=t1/t2;
			}
	for(i=1;i<n;i++)
		for(j=i+1;j<=n;j++)
			if(b[i]==b[j])nr++;
	fprintf(g,"%d\n",nr);
		fclose(g);
		return 0;
}