#include <fstream>
#include <algorithm>
#include <cmath>
#include <iostream>
using namespace std;
ifstream fin ("trapez.in");
ofstream fout ("trapez.out");
int sol;
#define eps 0.0001

struct punct{
int x,y;
};

struct segm{
punct a,b;
double tan;
bool operator < (const segm& S) const
    {
        return (b.y - a.y) * (S.b.x - S.a.x)
              - (S.b.x - a.x)* (S.b.y - S.a.y)< 0;
    }
};
segm S [10000001];
punct p [1001];

bool Vertical(punct A, punct B)
{
    return fabs(A.x - B.x) < eps;
}
double Panta(punct A, punct B)
{ if(Vertical (A,B))
		return -1;
    return (double)(B.y - A.y) / (B.x - A.x);
}


int main() {
	 int i,j,nrseg=0,n,cnt=1;
	fin >> n;
	for(i = 0; i < n; i ++ )
		fin >> p[i].x >> p[i].y;
	//Construiesc Segmente
	for( i = 0; i < n;  i ++ )
		for( j= i + 1; j < n; j ++) {
			S [ nrseg ].a.x = p [i].x;
			S [ nrseg ].a.y = p [i].y;
			S [ nrseg ].b.x = p [j].x;
			S [ nrseg].b.y = p [j].y;
			S [nrseg++].tan=Panta(p[i],p[j]);
			}

sort(S,S+nrseg);

for( i = 1; i < nrseg; i ++)
	if(fabs (S [i].tan-S [i-1].tan)<eps)
			cnt++;
		else {
					sol+=cnt*(cnt-1)/2;
		cnt=1;
		}
		fout << sol;
	
}