#include <stdio.h>
#include <math.h>
#include <algorithm>

#define eps 1
#define INF 10E20

//using namespace std;

class POINT {
public:
	double x, y;
	void read(char type = 'i') {//i = long, d = double
		long ax, ay;
		double bx, by;
		if(type == 'i') {
			scanf("%ld%ld", &ax, &ay);
			x = ax;
			y = ay;
		}
		else {
			scanf("%lf%lf", &bx, &by);
			x = bx;
			y = by;
		}
	}
	double panta(POINT &other) {
		if(other.x == x)
			return INF;
		else return (other.y - y) / (other.x - x);
	}
};

long n, nm;
double pante[500000], p, lp;
POINT P[1001];

int cmp(double x, double y) {
	if(x > y)
		return 0;
	else return 1;
}

int main() {
	long i, j, i1, k = 0, d, cs;
	freopen("trapez.in", "r", stdin);
	freopen("trapez.out", "w", stdout);
	scanf("%ld", &n);
	for(i = 1; i <= n; i++)
		P[i].read('i');
	for(i = 1; i <= n; i++)
		for(j = i + 1; j <= n; j++) {
			p = P[i].panta(P[j]);
			pante[++nm] = p;
		}
	std::sort(pante[1], pante[nm + 1]);
	cs = 1;
	lp = pante[i];
	for(i = 2; i <= nm + 1; i++) {
		if(lp == pante[i])
			cs++;
		else {
			lp = pante[i];
			k += (cs * (cs - 1)) / 2;
			cs = 1;
		}
	}
	printf("%ld", k);
	return 0;
}