#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
int n,m;
struct pct
{
    int x,y;
}a[1005];
bool cmp(pct X,pct Y)
{
    if(X.x==Y.x)
        return X.y<Y.y;
    return X.x<Y.x;
}
vector<double>b;
int main()
{
    f>>n;
    for(int i=1;i<=n;i++)
        f>>a[i].x>>a[i].y;
    sort(a+1,a+n+1,cmp);
    for(int i=1;i<=n;i++)
        for(int j=i+1;j<=n;j++)
        {
            double m;
            if(a[i].x==a[j].x)
                m=1e5;
            else
                m=(double)(a[j].y-a[i].y)/(a[j].x-a[i].x);
            b.push_back(m);
        }
    sort(b.begin(),b.end());
    int ans=0,nr=1;
    for(int i=0;i<b.size()-1;i++)
    {
        if(b[i]==b[i+1])
            nr++;
        else
            ans=ans+(nr*(nr-1)/2),nr=1;
    }
    ans=ans+(nr*(nr-1)/2);
    g<<ans;
    return 0;
}