#include <iostream>
#include <fstream>
#include <algorithm>
#include <cmath>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
struct pct{
            int x;
            int y;
            };
pct v[1001];
double a[500510];
int main()
{int n,i,j;
f>>n;
for(i=1;i<=n;i++)
f>>v[i].x>>v[i].y;
    int p=0;
for(i=1;i<=n-1;i++)
    for(j=i+1;j<=n;j++)
    a[++p]=(double)(((double)((double)v[i].y-(double)v[j].y))/((double)((double)v[i].x-(double)v[j].x)));
sort(a+1,a+p+1);
int nr,s;
nr=1;
s=0;
for(i=1;i<=p;i++)
{
    if(a[i]==a[i-1])
    nr++;
    else
    {
    s=s+nr*(nr-1)/2;
    nr=1;
    }
}
 s=s+nr*(nr-1)/2;
    g<<s;
    return 0;
}