#include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
using namespace std;
int N;
vector<double>X;
int op[10000];
main()
{
	cin>>N;
	for(int i=0;i<N;i++)
	{
		int x,y;cin>>x>>y;
		X.push_back(atan2(y,x));
	}
	sort(X.begin(),X.end());
	for(int i=0;i<N;i++)
	{
		double x=X[i];
		X.push_back(x+2*M_PI);
	}
	int id=0;
	long ans=0;
	for(int i=0;i<N;i++)
	{
		while(id<2*N&&X[id]<X[i]+M_PI+1e-10)id++;
		int jd=id;
		for(int j=i+1;j<N;j++)
		{
			if(X[j]>X[i]+M_PI-1e-10)break;
			while(jd<2*N&&X[jd]<X[j]+M_PI-1e-10)jd++;
			ans+=jd-id;
		}
	}
	cout<<ans/2<<endl;
}