#include <bits/stdc++.h>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
map <long double,int>m;
map <long double,int>::iterator it;
int n,x[1005],y[1005],i,j,s;
long long sol;
long double c;
int main()
{
    f>>n;
    for(i=1;i<=n;i++)
      f>>x[i]>>y[i];
    for(i=1;i<=n;i++)
      for(j=i+1;j<=n;j++)
    {
      if(x[i]==x[j])
        m[-10000]++;
      else
      {c=(long double)(y[j]-y[i])/(x[j]-x[i]);
      m[c]++;}
    }
    for(it=m.begin();it!=m.end();it++)
    {
      c=it->second;
      s=it->first;
      sol+=c*(c-1)/2;
    }
    g<<sol;
    return 0;
}