#include <fstream>
#include <algorithm>
#define dim 1000
#define x first
#define y second
using namespace std;
ifstream fin ("trapez.in");
ofstream fout ("trapez.out");
pair <int,int> v[dim+1],p[dim*(dim-1)/2+1];
int n,k;
void cmmdc (int &x,int &y)
{
    if (x==0)
    {
        y=1;
        return ;
    }
    if (y==0)
    {
        x=1;
        return ;
    }
    int r,a=x,b=y;
    if (a<0)
        a=-a;
    while (b!=0)
    {
        r=a%b;
        a=b;
        b=r;
    }
    x/=a,y/=a;
}
int main ()
{
    fin>>n;
    for (int i=1; i<=n; i++)
        fin>>v[i].x>>v[i].y;
    sort (v+1,v+n+1);
    for (int i=1; i<=n; i++)
    {
        for (int j=i+1; j<=n; j++)
        {
            int a=v[j].y-v[i].y;
            int b=v[j].x-v[i].x;
            cmmdc (a,b);
            p[++k]=make_pair (a,b);
        }
    }
    sort (p+1,p+k+1);
    long long sol=0,nr=1;
    for (int i=2; i<=k; i++)
    {
        if (p[i]==p[i-1])
            nr++;
        else
            sol+=nr*(nr-1)/2,nr=1;
    }
    sol+=nr*(nr-1)/2;
    fout<<sol;
    return 0;
}