#include <iostream>
#include <fstream>
#include <map>
using namespace std;

int N, r;
pair<int, int> p[1001];
map<pair<int, int>, int> m;

void read()
{
    //cin>>N;
    ifstream f("trapez.in");
    f>>N;
    for (int i=0, x, y;i<N;i++)
    {
        //cin>>x>>y;
        f>>x>>y;
        p[i]={x, y};
    }
}

int gcd(int a, int b)
{
    if (a==0)
        return b;
    if (b==0)
        return a;
    int r=a%b;
    while (r)
    {
        a=b;
        b=r;
        r=a%b;
    }
    return b;
}

void count_lines()
{
    int x, y, z;
    for (int i=0;i<N;i++)
    {
        for (int j=i+1;j<N;j++)
        {
            if (p[i].first==p[j].first)
                m[{0,0}]++;
            else
            {

                x=p[i].second-p[j].second;
                y=p[i].first-p[j].first;
                if (y<0)
                    y=-y, x=-x;
                z=gcd(x, y);
                x/=z;
                y/=z;
                m[{x,y}]++;
            }
        }
    }
    for (map<pair<int, int>,int>::iterator i=m.begin();i!=m.end();i++)
    {
        //cout<<'('<<(i->first).first<<' '<<(i->first).second<<") "<<i->second<<'\n';
        r+=(i->second)*(i->second-1)/2;
    }
}

void write()
{
    //cout<<r;
    ofstream g("trapez.out");
    g<<r;
}

int main()
{
    read();
    count_lines();
    write();
}