#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>

typedef struct 
{
	int x;
	int y;
} xy;

xy A[1001];
double B[1000001];
int N;
int nr = 0;
int nr1 = 0;
int nr2 = 0;
int acc = 0;

void citire(void)
{
	FILE *f = fopen("trapez.in","r");
	
	fscanf(f,"%d ",&N);
	for(int i=1;i<=N;i++)
		fscanf(f,"%d %d",&A[i].x,&A[i].y);
	
	fclose(f);
}

void creare(void)
{
	for(int i=1;i<=N;i++)
		for(int j=i+1;j<=N;j++)
			B[++acc] = (double)(A[i].y-A[j].y)/(A[i].x-A[j].x);
}

void calc(void)
{
	int j;
	int i = 1;
	int d;
	while(i<acc)
	{
		j = i+1;
		d = 0;
		while(j<=acc && B[i] == B[j])
		{
			d ++;
			j ++;
		}
		nr += (d*(d+1))/2;
		i = j;
	}
	nr += (nr1*(nr1-1))/2;
	nr += (nr2*(nr2-1))/2;
}

long int poz(int li,int ls)
{
	double a = B[(li+ls)/2];
	B[(li+ls)/2] = B[li];
	B[li] = a;
	int c;
	int i1 = 0;
	int j1 = -1;
	while(li<ls)
	{
		if(B[li]>B[ls])
		{
			a = B[li];
			B[li] = B[ls];
			B[ls] = a;
			c = -i1;
			i1 = -j1;
			j1 = c;
		}
		li += i1;
		ls += j1;
	}
	return li;
}

void quicksort(int li,int ls)
{
	if(li<ls)
	{
	long int k = poz(li,ls);
	quicksort(li,k-1);
	quicksort(k+1,ls);
	}
}

int main()
{
	FILE *f = fopen("trapez.out","w");
	
	citire();
	creare();
	quicksort(1,acc);
	calc();
	fprintf(f,"%d",nr);
	
	fclose(f);
	return 0;
}