#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

pair<int, int>p[1005];
pair<int, int>pa;

int n, s;


vector<pair<int, int>>fr;

int cmmdc(int x, int y)
{
    if(y==0)
        return x;
    cmmdc(y, x%y);
}

int rez(int n)
{
    return n*(n-1)/2;
}

int cmp(pair<int, int>a, pair<int, int>b)
{
    return a.first*b.second<a.second*b.first;
}

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

    scanf("%d", &n);
    for(int i=1;i<=n;i++)
    {
        int x, y;
        scanf("%d %d", &p[i].first, &p[i].second);
    }

    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
        {
            pa.first=p[j].second-p[i].second;
            pa.second=p[j].first-p[i].first;
            int diviz=cmmdc(pa.first, pa.second);
            pa.first/=diviz;
            pa.second/=diviz;
            fr.push_back({pa.first, pa.second});
        }

    sort(fr.begin(), fr.end(), cmp);
    pair<int,int>x;
    x.first=fr[0].first;
    x.second=fr[0].second;
    int nr=1;
    for(int i=1;i<fr.size();i++)
    {
        if(fr[i].first==x.first && fr[i].second==x.second)
            nr++;
        else
        {
            s+=rez(nr);
            x.first=fr[i].first;
            x.second=fr[i].second;
            nr=1;
        }
    }
    printf("%d", s);

    return 0;
}