#include <fstream>
using namespace std;

double v[1<<19];
int a[1<<10],b[1<<10];

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

int main()
{
	int n,i,j,k=0;
	long long nr=0,q=0;
	in>>n;
	for (i=1;i<=n;i++)
	{
		in>>a[i]>>b[i];
		for (j=1;j<i;j++)
		{
			if (b[i]==b[j])
			{
				q++;
				continue;
			}
			v[++k]=(double)(a[i]-a[j])/(b[i]-b[j]);
		}
	}
	sort(v+1,v+k+1);
	for (i=1;i<k;i++)
		for (j=i+1;v[i]==v[j] && j<=k;j++,nr++);
	nr+=(long long)q*(q-1)/2;
	out<<nr<<"\n";
	return 0;
}