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

#define eps 1.e-18
#define INF 1.e20
#define eq2(x, y) (fabs((x)-(y))<eps)
#define eq(x, y) ((x)-(y)==0)
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(eq(other.x, x))
			return INF;
		else return (other.y - y) / (other.x - x);
	}
};

class double_ {public:
	double x;
};

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

int cmp(double x, double y) {
	if(x-y >=eps)
		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;
		}
	sort(&pante[1], &pante[nm + 1], cmp);
	//sort(&pante[1], &pante[nm + 1]);
	i=1;
	cs = 1;
	lp = pante[i];
	for(i = 2; i <= nm + 1; i++) {
		if(eq2(lp, pante[i]))
			cs++;
		else {
			lp = pante[i];
			k += (cs * (cs - 1)) / 2;
			cs = 1;
		}
	}
	printf("%ld", k);
	return 0;
}