#include<stdio.h>
#include<vector>
#include<algorithm>
using namespace std;
#define NMAX 1001
int x[NMAX],y[NMAX],n;
vector<double> m;
int main()
{
	int i,j,contor=0;;
	m.reserve(NMAX*NMAX);
	freopen("trapez.in","r",stdin);
	freopen("trapez.out","w",stdout);
	scanf("%d",&n);
	for(i=1;i<=n;i++)
		scanf("%d%d",&x[i],&y[i]);
	for(i=1;i<n;i++)
		for(j=i+1;j<=n;j++)
			if(x[j]==x[i])
			{
				m.push_back(200000);
			
				}
			else
					m.push_back((double)(y[j]-y[i])/(x[j]-x[i]));
		sort(m.begin(),m.end());

	for(i=0;i<m.size()-1;i++)
		for(j=i+1;m[i]==m[j];j++)
			contor++;
	printf("%d",contor);
	return 0;
}