#include <cstdio>
#include <algorithm>
using namespace std;
int a[1002],b[1002],pa,k,n,nr;
double p[1000003];
int main()
{
freopen("trapez.in","r",stdin);
freopen("trapez.out","w",stdout);
scanf("%d",&n);
for(int i=1;i<=n;++i)scanf("%d%d",&a[i],&b[i]);
for(int i=1;i<n;++i)
for(int j=i+1;j<=n;++j)
k++,p[k]=(double)(a[i]-a[j])/(b[i]-b[j]);
sort(p+1,p+k+1);
for(int i=1;i<=k;++i)
{
nr=1;
while(p[i]==p[i+1]&&i+1<=k)++nr,++i;
pa=pa+(nr-1)*nr/2;
}
printf("%d",pa);
fclose(stdin);fclose(stdout);
return 0;
}