#include <fstream>
#include <algorithm>
using namespace std;

ifstream fin("trapez.in");
ofstream fout("trapez.out");

#define x first
#define y second
#define NMAX 1001
#define PII pair <int, int>

int i, j, N, nr;
int cnt;
int ANS;

PII P[NMAX];
PII Pante[NMAX * NMAX];

struct cmp {
	bool operator() (const PII &a, const PII &b) const {
		if (a.x * b.y == b.x * a.y) return 1;
		else
			if (a.x * b.y < b.x * a.y) return 1;
		return 0;
	};
};

int main() {
	fin >> N;
	for (i = 1; i <= N; ++i) 
		fin >> P[i].x >> P[i].y;
	for (i = 1; i <= N; ++i) {
		for (j = i + 1; j <= N; ++j) {
			Pante[++cnt].x = P[j].x - P[i].x;
			Pante[cnt].y = P[j].y - P[i].y;
		}
	}
	sort(Pante + 1, Pante + cnt + 1, cmp());
	for (i = 2; i <= cnt; ++i) {
		nr = 0;
		while (Pante[i].x * Pante[i - 1].y == Pante[i].y * Pante[i - 1].x) ++nr, ++i;
		ANS += (nr * (nr - 1) / 2);
		if (nr == 1) ++ANS;
	}
	fout << ANS << '\n';
	return 0;
}