#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
struct eu{int x,y;};
eu v[1001];
struct eu2{int x,y;};
eu2 vc[1000001];
int n,i,j,k,l,m,cate,s;
bool sorting(eu2 a,eu2 b)
    {
    if(a.x<b.x||a.x==b.x&&a.y<b.y)
        return 1;
    return 0;
    }
int cmmdc(int a,int b)
    {
    int r;
    while(b!=0)
        {
        r=a%b;
        a=b;
        b=r;
        }
    return a;
    }
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(i=1;i<n;i++)
    for(j=i+1;j<=n;j++)
        {
        cate++;
        vc[cate].x=v[j].x-v[i].x;
        vc[cate].y=v[j].y-v[i].y;
        int h;
        h=cmmdc(abs(vc[cate].x),abs(vc[cate].y));
        vc[cate].x/=h;
        vc[cate].y/=h;
        }
sort(vc+1,vc+cate+1,sorting);
int k=0,nr=0;
for(i=1;i<=cate;i++)
    {
    if(vc[i].x==vc[i-1].x&&vc[i].y==vc[i-1].y||vc[i].x==0&&vc[i-1].x==0||vc[i].y==0&&vc[i-1].y==0)
        nr++;
    else
        {
        s+=nr*(nr-1)/2;
        nr=1;
        }
    }
printf("%d",s);
return 0;
}