#include <bits/stdc++.h>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
int n,x[1005],y[1005],i,j,s,k,sc;
long long sol;
long double c,a[1005*1005];
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])
        a[++k]=-10000;
      else
      {c=(long double)(y[j]-y[i])/(x[j]-x[i]);
     a[++k]=c;}
    }
    sort(a+1,a+k+1);

    for(i=2;i<=k;i++)
    {
      if(a[i]==a[i-1])
        sc++;
        else
      {sol+=sc*(sc+1)/2;sc=0;}
    }
    g<<sol;
    return 0;
}