#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;

const double INF = 1.e+12;
const double eps = 1.e-14;

struct POINT
{
    int x,y;
} v[1001];

double p[550000];

bool vertical(POINT A,POINT B)
{
    return fabs(B.x-A.x)<eps;
}
double panta(POINT a,POINT b)
{
    if(vertical(a,b))
        return INF;
    else
        return ((double)b.y-a.y)/(b.x-a.x);
}
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,i,j;
    scanf("%d",&n);
    for(i=1; i<=n; ++i)
        scanf("%d%d",&v[i].x,&v[i].y);
    int k=0,l=1;
    long long t=0;
    for (i=1; i<=n; ++i)
        for (j=i+1; j<=n; ++j)
            p[++k] = panta(v[i],v[j]);
    sort (p+1, p+k+1);
    for (i=2; i<=k; ++i)
    {
        if(fabs(p[i-1]-p[i])<eps)
            l++;
        else
        {
            t+=(long long)l*(l-1)/2;
            l=1;
        }
    }
    t+=(long long)l*(l-1)/2;
    printf("%lld\n",t);
    return 0;
}