#include <bits/stdc++.h>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
int i,j,n,nr,a[1005],b[1005],ans;
vector<double> v;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)fin>>a[i]>>b[i];
    for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++)
            v.push_back((double)(a[i]-a[j])/(b[i]-b[j]));
    sort(v.begin(),v.end());
    n=v.size();
    for(i=0;i<n;i++)
    {
        nr=1;
        while(i<n-1&&v[i]==v[i+1]){i++;nr++;}
        ans+=nr*(nr-1)/2;
    }
    fout<<ans;
    return 0;
}