#include <cstdio>
#include <climits>
#include <algorithm>
#define eps 1e-12
using namespace std;
struct nod
{
    int x,y;
};
nod a[1500];
int n,i,nr,len,j;
long long sol;
double v[1000005];
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    scanf("%d\n",&n);
    for (i=1; i<=n; i++)
        scanf("%d %d\n",&a[i].x,&a[i].y);
    for (i=1; i<=n; i++)
    {
        for (j=i+1; j<=n; j++)
        {
            if (a[i].x-a[j].x!=0)
            {
                v[++nr]=(double)(a[i].y-a[j].y)/(a[i].x-a[j].x);
            }
            else v[++nr]=INT_MAX;
        }
    }
    sort(v+1,v+nr+1);
    i=2;
    while (i<=nr)
    {
        len=1;
        while (v[i]-v[i-1]<eps&&v[i]-v[i-1]>-eps)
        {
            i++;
            len++;
        }
        sol+=1LL*len*(len-1)/2;
        if (len==1)i++;
    }
    printf("%lld\n",sol);
    return 0;
}