#include <stdio.h>
#include <math.h>
#include <algorithm>
#define ABS 0.000000000000001
using namespace std;
struct pt
{
    int x,y;
}v[1001];
double dr[1000001];
bool comp(pt a,pt b)
{
    if(a.x==b.x)
        return a.y<b.y;
    return a.x<b.x;
}
int main()
{
    int n,i,c,j,nr;
    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);
    sort(v+1,v+1+n,comp);
    c=0;
    for(i=1; i<=n; i++)
        for(j=i+1; j<=n; j++)
        {
            if(v[i].x==v[j].x)
                dr[++c]=1.570796326794897;
            else
                dr[++c]=atan2(v[j].y-v[i].y,v[j].x-v[i].x);
        }
    sort(dr+1,dr+1+c);
    nr=0;
    for(i=1; i<=c;)
    {
        j=i;
        while(j<=c && fabs(dr[j]-dr[i])<ABS)
            j++;
        nr+=(j-i)*(j-i-1)/2;
        i=j;
    }
    printf("%d\n",nr);

    return 0;
}