#include <stdio.h>
#include <stdlib.h>
#include <math.h>
struct ceva2
{
	long long a,b;
};

int compare( const void* a, const void* b ) {
	ceva2* aa = (ceva2*) a;
   ceva2* bb = (ceva2*) b;
   if( aa->a*bb->b<bb->a*aa->b) return -1;
   else if(aa->a*bb->b==bb->a*aa->b) return 0;
   else return 1;
 }   
struct ceva
{
	long long  x,y;
};
ceva a[1005];
ceva2  b[1000010];
int main()
{
	FILE *in,*out;
	int i,n,nr,nr2,j,nr3=0,nr4=0,nr5=0;
	in=fopen("trapez.in","r");
	out=fopen("trapez.out","w");
	//ciur(50000);
	fscanf(in,"%d",&n);
	for (i=1;i<=n;i++)
		fscanf(in,"%lld%lld",&a[i].x,&a[i].y);
	nr=0;
	for (i=1;i<=n;i++)
	{
		for (j=i+1;j<=n;j++)
		{
			
			if (a[i].y-a[j].y!=0&&a[i].x-a[j].x!=0)
			{
				nr++;
				b[nr].a=a[i].x-a[j].x;
				b[nr].b=a[i].y-a[j].y;
			}
			if (a[i].y-a[j].y==0)
				nr4++;
			if (a[i].x-a[j].x==0)
				nr5++;
				//b[nr]=(double)(a[i].x-a[j].x)/(double)(a[i].y-a[j].y);
			/*}
			else
			{
				b[nr].a=-4000000001;
				b[nr].b=1;
			}
			if (a[i].x-a[j].x==0)
			{
				b[nr].a=4000000001;
				b[nr].b=1;
			}*/
		}
	}
	qsort(b+1,nr,sizeof(b[1]),compare);
	nr2=nr4*(nr4-1)/2+nr5*(nr5-1)/2;
	for (i=1;i<nr;i++)
	{
		nr3=0;
		while (b[i].a*b[i+1].b==b[i+1].a*b[i].b)
		{
			nr3++;
			i++;
		}
		if (nr3)
			nr2+=nr3*(nr3-1)/2;
		
	}
	fprintf(out,"%d\n",nr2);
	fclose(in);
	fclose(out);
	return 0;
}