#include <algorithm>
#include <iostream>
#include <fstream>
#include <map>
 
#define INF 1000000
 
using namespace std;
 
ifstream f("trapez.in");
ofstream g("trapez.out");
 
int sol , nr , n , x = 1;
 
double panta[1000005];
 
pair <double , double> a[1005];
 
int main() {
    f >> n;
 
    for(int i = 1 ; i <= n ; ++i) {
        f >> a[i].first >> a[i].second;
    }
 
    for(int i = 1 ; i <= n ; ++i) {
        for(int j = i + 1 ; j <= n ; ++j) {
            if(a[j].second == a[i].second) {
                panta[++nr] = INF;
            }
            else {
                panta[++nr] = (a[j].first - a[i].first) / (a[j].second - a[i].second);
            }
        }
    }
 
    sort(panta + 1 , panta + nr + 1);
 
    for(int i = 2 ; i <= nr ; ++i) {
        if(panta[i] == panta[i - 1]) {
            ++x;
        }
 
        else {
            sol = sol + x * (x - 1) / 2;
            x = 1;
        }
    }
 
    sol = sol +  x * (x - 1) / 2;
 
    g << sol;
    return 0;
}