#include<cstdio>
#define p first
#define x second.first
#define y second.second
#include<vector>
#define eps 1e-12
#define inf 2000000002
#include<algorithm>

using namespace std;

pair<double,pair<int,int> > s[1000002];
int n,nr,nr1,i,j,lg;
double last;
pair<int,pair<int,int> > a[1002];

double panta(int i,int j)
{
    double dy,dx;
    dy=a[i].y-a[j].y;
    dx=a[i].x-a[j].x;
    if(dx==0)
    {
        return inf;
    }
    return (dy/dx);
}

bool cmp(pair<double,pair<int,int> > i,pair<double,pair<int,int> > j)
{
    if(i.first+eps>j.first+eps)
    {
        return true;
    }
    return false;
}

int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&a[i].x,&a[i].y);
    }
    nr1=0;
    for(i=1;i<n;i++)
    {
        for(j=i+1;j<=n;j++)
        {
            s[nr1++]=make_pair(panta(i,j),make_pair(i,j));
        }
    }
    sort(s,s+nr1);
    lg=0;
    last=s[0].p;
    for(i=0;i<nr1;i++)
    {
        if(last-s[i].p<eps&&last-s[i].p>-eps)
        {
            lg++;
        }
        else
        {
            nr+=lg*(lg-1)/2;
            lg=1;
            last=s[i].p;
        }
    }
    printf("%d\n",nr);
}