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

struct P{int  x,y;};

P a[1001];
int n,Sum=0;
map<double,int> H;
map<double,int>::iterator it;

int main(){

    ifstream f("trapez.in");
    ofstream g("trapez.out");

    int Sum=0;
    f >> n;
    for(int i=1;i<=n;i++)
        f >> a[i].x >> a[i].y;

    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
            H[(double)(a[i].y-a[j].y)/(a[i].x-a[j].x)]++;

    for(it=H.begin();it!=H.end();it++)
        Sum+=(it->second)*(it->second-1)/2;

    g << Sum <<"\n";
}