#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#define eps 1e-14
#define inf 2000000000

using namespace std;

class POINT {
	
private:
	long x;
	long y;
public:
	POINT(){}
	
	void set(long a, long b){
		
		x=a;
		y=b;
		
	}

	long gx ()
	{
		return x;
	}
	long gy ()
	{
		return y;
	}
	
	friend double panta (POINT &P1, POINT &P2){
		
		if(P2.x==P1.x)
			return inf;
		return (double)((double)P2.y-P1.y)/(P2.x-P1.x);
	}
};

POINT P[1001];
double pante[1000*1001];
long a,b,k,n,i,j,num;
bool cmp (double x, double y)
{
	return x-y<-eps;
}

int main () {
	
	freopen("trapez.in","r",stdin);
	freopen("trapez.out","w",stdout);
	
	scanf("%ld",&n);
	
	for(i=1;i<=n;i++)
	{
		scanf("%ld%ld",&a,&b);
		P[i].set(a,b);
	}
	
	for(i=1;i<=n;i++)
		for(j=1;j<i;j++)
			pante[++num]=panta(P[i],P[j]);
	sort(pante+1,pante+num+1,cmp);
	
	pante[++num]=inf;
	long l=1,s=0;
	
	for(i=1;i<num;i++)
		if(fabs(pante[i+1]-pante[i])<eps)
			l++;
		else
			{
				s+=l*(l-1)/2;
				l=1;
			}
	
	printf("%ld\n",s);
	
	return 0;
}