#include <cstdio>
#include <math.h>
#include <stdlib.h>

const unsigned NMAX = 1005, KEYLENGTH = 16;
int SALT = 2;

struct hash_el
{ double v; unsigned int nr; };

inline int hk(double x)
{
	//int mask = ~(~0 << KEYLENGTH);
	const double A = 0.618;
	double t = A * x;
	const unsigned int M = 1 << KEYLENGTH;
	return floor( (t - floor(t)) * (M - 1) ) + 1;
}

bool add(hash_el* ls, double x)
{
	unsigned int m = ls -> nr, i;
	bool ok = false, added = false;
	for (i = 1; i <= m; ++i) {
		if (ls[i].v == x) {
			added = true;
			++ls[i].nr;
			if (ls[i].nr == 2) ok = true;
			break;
		}
	}
	if (!added) {
		i = ++(ls[0].nr);
		ls[i].nr = 1;
		ls[i].v = x;
	}
	if (ok && !(ls -> v)) {
		ls -> v = 1;
		return 1;
	}
	else return 0;
}

hash_el hash[(1 << KEYLENGTH) + 1][12] = {}, *hl[(1 << KEYLENGTH) + 5] = {};

int main()
{
	unsigned int rasp = 0;
	int N, x[NMAX] = {}, y[NMAX] = {};
	int ii, jj, key, hllen = 0, k, m;
	double panta, nr, nu;
	hash_el **i, *j;
	
	
	freopen("trapez.in", "r", stdin);
	freopen("trapez.out", "w", stdout);
	scanf("%d", &N);
	for (ii = 0; ii != N; ++ii)
		scanf("%d %d\n", &x[ii], &y[ii]);
	for (ii = 0; ii != N; ++ii)
		for (jj = ii + 1; jj != N; ++jj) {
			nr = y[jj] - y[ii];
			nu = x[jj] - x[ii];
			if (!nu) {
				key = 0;
				panta = 2500000000;
			}
			else {
				panta = nr / nu;
				key = hk(panta);
			}
			if ( add(hash[key], panta) ) hl[hllen++] = hash[key];
		}
	for (i = hl; *i; ++i) {
		j = *i;
		m = j -> nr;
		for (k = 1; k <= m; ++k)
			rasp += j[k].nr * (j[k].nr - 1) / 2;
	}

	printf("%u\n", rasp);

	fclose(stdin);
	fclose(stdout);
	return 0;
}