#include<fstream>
#define maxn 1005

using namespace std;

ifstream f("trapez.in");
ofstream g("trapez.out");

struct panta
{
    int x;
    int y;
} a[maxn],b[maxn*maxn],c[maxn*maxn],k;

int n,i,j,p,q,r;

long long rez;

int mod(int a)
{
    if(a<0) return -a;
    return a;
}

bool fcomp(panta a, panta b)
{
    return a.x*b.y<a.y*b.x;
}

bool comp(panta a,panta b)
{
    return (a.x==0&&b.x==0)||(a.y==0&&b.y==0)||(a.x==b.x&&a.y==b.y);
}

int main()
{
    f>>n;

    for(i=1;i<=n;++i)
        f>>a[i].x>>a[i].y;

    for(i=1;i<=n;++i)
        for(j=i+1;j<=n;++j)
        {
            k.x=a[i].y-a[j].y;
            k.y=a[i].x-a[j].x;
            if(k.x<0&&k.x<0)
                k.x=-k.x,k.y=-k.y,b[++p]=k;
            else
                if(k.x<0||k.y<0)
                    k.x=mod(k.x),k.y=mod(k.y),c[++q]=k;
                else
                    b[++p]=k;
        }

    sort(b+1,b+p+1,fcomp);
    sort(c+1,c+q+1,fcomp);

    r=1;
    for(i=2;i<=p;++i)
        if(!comp(b[i],b[i-1]))
            rez+=(i-r)*(i-r-1)/2,r=i;

    rez+=(i-r)*(i-r-1)/2;

    r=1;

    for(i=2;i<=q;++i)
        if(!comp(c[i],c[i-1]))
            rez+=(i-r)*(i-r-1)/2,r=i;

    rez+=(i-r)*(i-r-1)/2;

    g<<rez<<"\n";

    f.close();
    g.close();

    return 0;
}