#include <bits/stdc++.h>

using namespace std;

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

int main()
{
    int N; f>>N;
    vector<pair<int,int>> V(N);
    for(auto &p:V) f>>p.first>>p.second;
    map<pair<int,int>,int> A;
    for(int i=0;i<V.size();i++)
        for(int j=i+1;j<V.size();j++)
        {
            int a=V[i].second-V[j].second,
                b=V[j].first-V[i].first;
            A[{a/__gcd(a,b),b/__gcd(a,b)}]++;
        }
    uint64_t result=0;
    for(auto a:A)
    {
        uint64_t nr=a.second;
        result+=1LL*nr*(nr-1)/2;
    }
    g<<result;

    return 0;
}