#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
int n,nr,ct,z;
double m[1000005],x[1001],y[1001];
int main()
{
    int i,j;
fin>>n;
for(i=1;i<=n;i++)
    fin>>x[i]>>y[i];
for(i=1;i<n;i++)
    for(j=i+1;j<=n;j++)
        if(x[i]==x[j])
            m[++nr]=1e9;
        else
            m[++nr]=(y[j]-y[i])/(x[j]-x[i]);
sort(m+1,m+nr+1);
for(i=1;i<nr;i++)
{   z=1;
    while(m[i]==m[i+1])
        z++,i++;
    ct=ct+z*(z-1)/2;
}
fout<<ct;
    return 0;
}