#include <cstdio>
#include <algorithm>
using namespace std;
double v[1000002];
int a[1002],b[1002];

int main()
{
	int n,i,j,k=0;
	long long nr=0,q=0;
	freopen("trapez.in","r",stdin);
	freopen("trapez.out","w",stdout);
	scanf("%d",&n);
	for (i=1;i<=n;i++)
		{
			scanf("%d %d",&a[i],&b[i]);
			for (j=1;j<i;j++)
				if (b[i]==b[j]) q++; else
					v[++k]=(double)(a[i]-a[j])/(b[i]-b[j]);
		}
	sort(v+1,v+k+1);
	for (i=1;i<k;i++)
		for (j=i+1;v[i]==v[j] && j<=k;j++,nr++);
	nr+=(long long)q*(q-1)/2;
printf("%lld",nr);
return 0;
}