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

using namespace std;

FILE *f,*s;

int n,i,j,k,l;

double v2[1000005];

struct punct
{
	double x;
	double y;
};

punct v1[1005];

int main()
{
	f=fopen("trapez.in","r");
	s=fopen("trapez.out","w");
	
	fscanf(f,"%d",&n);
	
	for(i=1;i<=n;i++)
		fscanf(f,"%lf %lf",&v1[i].x,&v1[i].y);
	
	k=1;
	for(i=1;i<n;i++)
	{
		for(j=i+1;j<=n;j++)
		{	
			v2[k]=(v1[i].x-v1[j].x)/(v1[i].y-v1[j].y);
			
			if(v2[k]<0)
				v2[k]*=-1;

			k++;
		}
	}	
	
	k--;
	
	sort(v2+1,v2+k+1);
	
	int rez=0;
	for(i=2;i<=k;i++)
	{
		if(v2[i]==v2[i-1])
			rez++;
	}	
		
	fprintf(s,"%d",rez);
	
	fclose(s);
	
	return 0;
}