#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
pair <int,int> v[1001],vec[1000001];
int sgn(pair <int,int> a)
{
    int rez;
    if(a.first==0)
        rez=0;
    else if((a.first<0)+(a.second<0)==1)
        rez=-1;
    else
        rez=1;
    return rez;
}
bool cmp(pair <int,int> a,pair <int,int> b)
{
    int sgn1=sgn(a),sgn2=sgn(b);
    if(sgn1!=sgn2)
        return sgn1<sgn2;
    if(sgn1==0)
        return 1;
    if(sgn1==1)
        return abs(1LL*a.first*b.second)<abs(1LL*a.second*b.first);
    return 1LL*abs(a.first)*abs(b.second)>1LL*abs(a.second)*abs(b.first);
}
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,i,j,cntvert=0,cnt=0;
    cin>>n;
    for(i=1;i<=n;i++)
        cin>>v[i].first>>v[i].second;
    for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++)
        {
            if(v[i].first==v[j].first)//verticala
                cntvert++;
            else
                vec[++cnt]={v[i].second-v[j].second,v[i].first-v[j].first};
        }
    sort(vec+1,vec+cnt+1,cmp);
    long long rez=1LL*cntvert*(cntvert-1)/2;
    int cnt1=1;
    for(i=2;i<=cnt;i++)
        if(1LL*vec[i].first*vec[i-1].second==1LL*vec[i].second*vec[i-1].first)
            cnt1++;
        else
        {
            rez+=1LL*cnt1*(cnt1-1)/2;
            cnt1=1;
        }
    rez+=1LL*cnt1*(cnt1-1)/2;
    cout<<rez;
    return 0;
}