#include<fstream>
#include<algorithm>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
unsigned long long i,j,n,nr=0,sol=0,a=0,x[1001],y[1001];
double p[1000001];
int main()
{f>>n;
for(i=1;i<=n;++i)
	f>>x[i]>>y[i];
for(i=1;i<n;++i)
	for(j=i+1;j<=n;++j)
		if(y[i]==y[j])
		{++nr;
		p[nr]=1000000000;
		}
		else
		{++nr;
		p[nr]=(double)(x[j]-x[i])/(y[j]-y[i]);
		}
sort(p+1,p+nr+1);
for(i=2;i<=nr;++i)
	if(p[i]==p[i-1])
		++a;
	else
	{sol+=a*(a+1)/2;
	a=0;
	}
sol+=a*(a+1)/2;
g<<sol;
return 0;
}