#include<fstream>
#include<algorithm>
#define NMAX 1100
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
struct  pct {int x,y;} d[NMAX];
double p[NMAX*NMAX];
int i,n,j,k,sol,nr;
 
int main () 
{f>>n;
 for(i=1;i<=n;++i)
    f>>d[i].x>>d[i].y;
 for(i=1;i<=n;++i)
    for(j=i+1;j<=n;++j)
            p[++nr]=(double)(d[i].x-d[j].x)/(d[i].y-d[j].y);
    sort(p+1,p+1+nr);
    for(i=1;i<=nr;++i)
        {k=1;
         while(i<nr && p[i+1]==p[i]) {++i; k++;}
         sol+=k*(k-1)/2;
        }
    g<<sol<<"\n";
    g.close();
    return 0;
}