#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int compare( const void* a, const void* b ) {
	double* arg1 = (double*) a;
   double* arg2 = (double*) b;
   if( *arg1-*arg2<=-0.000000000000000000000000000001) return -1;
   else if( *arg1-*arg2<=0.000000000000000000000000000001&&*arg1-*arg2>=-0.000000000000000000000000000001 ) return 0;
   else return 1;
 }   
struct ceva
{
	int x,y;
};
ceva a[1005];
double  b[1000010];
int main()
{
	FILE *in,*out;
	int i,n,nr,nr2,j;
	in=fopen("trapez.in","r");
	out=fopen("trapez.out","w");
	//ciur(50000);
	fscanf(in,"%d",&n);
	for (i=1;i<=n;i++)
		fscanf(in,"%d%d",&a[i].x,&a[i].y);
	nr=0;
	for (i=1;i<=n;i++)
	{
		for (j=i+1;j<=n;j++)
		{
			nr++;
			if (a[i].y-a[j].y!=0)
				b[nr]=(double)(a[i].x-a[j].x)/(double)(a[i].y-a[j].y);
			else
				b[nr]=-2000000001; 
		}
	}
	qsort(b+1,nr,sizeof(b[1]),compare);
	nr2=0;
	for (i=1;i<nr;i++)
	{
		while (b[i+1]-b[i]<=0.000000000000000000000000000001)
		{
			nr2++;
			i++;
		}
		
	}
	fprintf(out,"%d\n",nr2);
	fclose(in);
	fclose(out);
	return 0;
}