#include	<iostream>
#include	<fstream>
#include	<vector> 
using namespace std;
vector < pair <long,long> > v,m;   // m=(Yb-Ya)/(Xb-Xa); 
ifstream f("trapez.in");
ofstream g("trapez.out");

int main() 
{
	int i,n,a,b,j,s=0;
	f>>n;
	for(i=0;i<n;i++)
	{
		f>>a>>b;
		v.push_back(make_pair(a,b));
		v[i].first=a;
		v[i].second=b;
	}
	for (i=0;i<n-1;i++)
	{
		for (j=i+1; j<n; j++)
		{
			a=v[j].second-v[i].second; //yb-ya
			b=v[j].first-v[i].first;   //xb-xa
			m.push_back(make_pair(a,b));
		}
	}
	for (i=0;i<m.size()-1;i++)
		for (j=i+1; j<m.size();j++)
			if ((m[i].first*m[j].second)==(m[i].second*m[j].first))
				s++;
	g<<s;
	g.close();
	return 0;
}