#include <stdio.h>
#include <algorithm>
#include <math.h>

using namespace std;
FILE *f=fopen("trapez.in","r");
FILE *g=fopen("trapez.out","w");

struct nod{
int x;
int y;
}v[1004];


double nr[500010],m,h,a1,a2;
int n,i,j,a,b,k,nr1,nr2,s,ct,ok;
int main()
{
fscanf(f,"%d",&n);
for(i=1;i<=n;i++)
fscanf(f,"%d%d",&v[i].x,&v[i].y);

for(i=1;i<=n;i++)
for(j=i+1;j<=n;j++)
{
 a=v[i].y-v[j].y;
 b=v[j].x-v[i].x;
 if (a==0)nr1++;
 else if (b==0)nr2++;
 else {m=(a*1.0/b);k++;nr[k]=-m;}
}
s=0;
if (nr1>1)s+=nr1*(nr1-1)/2;
if (nr2>1)s+=nr2*(nr2-1)/2;
sort(nr+1,nr+k+1);

ct=1;
for(i=1;i<=k;i++)
if (nr[i]==nr[i-1])ct++;
else {s+=ct*(ct-1)/2;ct=1;}



fprintf(g,"%d",s);
fclose(g);
return 0;
}