#include <cstdio>
#include <algorithm>
using namespace std;

struct nod
{int a;int b;} dr[1000002];

int cmp(const nod &x,const nod &y)
{ return x.a*y.b<x.b*y.a;}

int main()
{
	int n,i,j,nr=0,ox[1002],oy[1002],sol;
	freopen("trapez.in","r",stdin);
	freopen("trapez.out","w",stdout);
	scanf("%d",&n);
	for (i=1;i<=n;++i)
	{
		scanf("%d %d",&ox[i],&oy[i]);
		for (j=1;j<i;++j)
			++nr,dr[nr].a=oy[i]-oy[j],dr[nr].b=ox[i]-ox[j];
	}
	sort(dr+1,dr+nr+1,cmp);
	for (i=2;i<=nr;++i)
		while ((dr[i].a*dr[i-1].b==dr[i].b*dr[i-1].a) && (i<=nr)) ++i,++sol;
	printf("%d",sol);
		return 0;}