#include<fstream>
#include<algorithm>
#define INF 0x3f3f3f3f
using namespace std;

ifstream in("trapez.in");
ofstream out("trapez.out");

struct punct {
	long long  x,y;
};

punct v[1001];
int n,m;
double v1[1000005];


void solve() {
	double panta;
	
	int i,j,rez1=0;
	
	for(i=1;i<n;i++)
		for(j=i+1;j<=n;j++) {
			if(v[i].x==0&&v[j].x==0)
				panta=INF;
				else
				panta=(double) (double(v[j].y-v[i].y)/(double(v[j].x-v[i].x)));
				
				v1[++m]=panta;
		}
	sort(v1+1,v1+m+1);
			
	int rez=0,nrc=1;
	
	for(i=1;i<m;i++)
		if(v1[i]==v1[i+1])
			++nrc;
		else {
			rez=rez+(nrc)*(nrc-1)/2;
			nrc=1;
		}
	if(nrc>=2)
		rez=rez+(nrc)*(nrc-1)/2;
	
	out<<rez<<'\n';
}

int main() {
	int i;
	
	in >> n;
	
	for(i = 1; i<=n; i++)
		in >> v[i].x >> v[i].y;
	
	solve();
	
	return 0;
}