#include <stdio.h>
#define dim 1001
#define dim2 dim*(dim-1)/2

int n, x[dim], y[dim], nr[dim2], num[dim2], ct=0, fol[dim2];

void q_sort(int l, int r) {
	int i=l, j=r, x=(i+j)/2, h;
	do {
		while (nr[i]*num[x]<nr[x]*num[i]) ++i;
		while (nr[x]*num[j]<nr[j]*num[x]) --j;
		if (i<=j) {
			h=nr[i], nr[i]=nr[j], nr[j]=h;
			h=num[i], num[i]=num[j], num[j]=h;
			++i, --j;
		}
	} while (i<=j);
	if (i<r) q_sort(i, r);
	if (l<j) q_sort(l, j);
}

int main() {
	int i, j, sol, nr1=0, nr2=0, tmp;
	freopen("trapez.in", "r", stdin);
	freopen("trapez.out", "w", stdout);
	scanf("%d\n", &n);
	for (i=1; i<=n; ++i) scanf("%d %d\n", &x[i], &y[i]);
	for (i=1; i<n; ++i)
		for (j=i+1; j<=n; ++j) {
			++ct;
			nr[ct]=y[j]-y[i];
			num[ct]=x[j]-x[i];
			if (!nr[ct]) nr1++, ct--;
			if (!num[ct]) nr2++, ct--;
		}
		
	q_sort(1, ct);
	
	sol=nr1*(nr1-1)/2+nr2*(nr2-1)/2;
	tmp=1;
	for (i=2; i<=ct; ++i)
		if (nr[i-1]*num[i]==nr[i]*num[i-1]) tmp++;
		else {
			sol+=tmp*(tmp-1)/2;
			tmp=1;
		}
	
	printf("%d\n", sol);
	return 0;
}