#include <stdio.h>
#include <algorithm>
#define N 1001
#define INF (1<<30)
FILE *in,*out;
using namespace std;
struct pc
{
    double x, y;
};
struct segm
{
    pc a, b;
    double p;
    bool operator <(const segm &e) const
    {
        return p<e.p;
    }
};
pc a[N];
segm b[N*N];
int main()
{
    in=fopen("trapez.in", "rt" );
    out=fopen("trapez.out", "wt");
    int n, m=0, i, j, s=0, sol=0;
    fscanf(in,"%d ", &n);
    for(i=1;i<=n;i++)
    {
        fscanf(in,"%lf %lf ", &a[i].x, &a[i].y);
        for(j=1;j<i;j++)
        {
            m++;
            b[m].a=a[i];
            b[m].b=a[j];
            if(b[m].a.x==b[m].b.x)
            {
                b[m].p=INF;
            }
            else
            {
                b[m].p=(b[m].a.y-b[m].b.y)/(b[m].a.x-b[m].b.x);
            }
        }
    }
    sort(b+1, b+m+1);
    b[0].p=INF+2;
    for(i=1;i<=m+1;i++)
    {
        if(i==m+1||b[i].p!=b[i-1].p)
        {
            sol+=(s*(s-1)/2);
            s=1;
        }
        else
        {
            s++;
        }
    }
    fprintf(out,"%d", sol);
    fclose(in);
    fclose(out);
    return 0;
}