#include<cstdio>
#include<algorithm>
using namespace std;
int n,i,j,q,nr,l,D,I,R;
struct nod
{
    int x;
    int y;
}v[1005],p[499505];
int cmp(const nod a,const nod b)
{
    if (a.x==b.x) return a.y<=b.y;
    return a.x<b.x;
}
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    scanf("%d",&n);
    for (i=1;i<=n;i++)
    {
        scanf("%d %d",&v[i].x,&v[i].y);
        for (j=i-1;j>=1;j--)
        {
            if (v[j].y==v[i].y) p[++l].x=0,p[l].y=0;
            else
            {
                p[++l].x=(v[j].x-v[i].x);
                p[l].y=(v[j].y-v[i].y);
                D=p[l].x; I=p[l].y; R=D%I;
                while (R) D=I,I=R,R=D%I;
                p[l].x=p[l].x/I;
                p[l].y=p[l].y/I;
            }
        }
    }
    sort(p+1,p+l+1,cmp);
    int sol=0;
    for (i=2;i<=l;i++)
    {
        if ((p[i].x!=p[i-1].x)&&(sol)) nr=nr+(sol+1)*sol/2,sol=0;
        if ((p[i].x==p[i-1].x)&&(p[i].y==p[i-1].y)) sol++;
    }
    printf("%d",nr);
    return 0;
}