#include <iostream>
#include <algorithm>
#include <cstdio>
#define N 1005

using namespace std;

struct punct
{
    int x, y;
}v[N];

int nr, n, np;
struct panta
{
    int sus, jos;
}p[N*N];

void citire()
{
    scanf("%d\n", &n);
    for(int i=1;i<=n;i++)
        scanf("%d %d\n", &v[i].x, &v[i].y);
}

void pante()
{
    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
            if(v[i].x==v[j].x)
                nr++;
            else
                if(v[j].y>v[i].y)
                    p[++np].sus=v[j].y-v[i].y, p[np].jos=v[j].x-v[i].x;
                else
                    p[++np].sus=v[i].y-v[j].y, p[np].jos=v[i].x-v[j].x;
}

int cmp(panta e, panta f)
{
    return e.sus*f.jos<e.jos*f.sus;
}

int main()
{
    freopen("trapez.in", "r", stdin);
    freopen("trapez.out", "w", stdout);

    citire();
    pante();
    sort(p+1, p+np+1, cmp);
    nr=((nr-1)*nr)/2;
    for(int i=2;i<=np;i++)
        if(p[i-1].sus*p[i].jos==p[i].sus*p[i-1].jos)
            nr++;
    printf("%d", nr);
    return 0;
}