#include <iostream>
#include <fstream>
using namespace std;
int n,k=1,cont;
int nr;
struct point {float x,y;} p[1010];
struct line {float a,b,c;} dr[500510];
int main()
{
    ifstream f("trapez.in");
    ofstream g("trapez.out");
    f>>n;
    for(int i=1;i<=n;i++) f>>p[i].x>>p[i].y;
    for(int i=1;i<=n;i++)
        for(int j=i+1;j<=n;j++)
        {   nr++;
            dr[nr].a=p[i].y-p[j].y;
            dr[nr].b=p[j].x-p[i].x;
            dr[nr].c=-dr[nr].a*p[i].x-dr[nr].b*p[i].y;
        }
    for(int i=1;i<=nr;i++)
    {   for(int j=i+1;j<=nr;j++)
        {   if(dr[i].a*dr[j].b-dr[j].a*dr[i].b==0) cont++;
        }
    }
    g<<cont;
}