#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 LL long long
#define PII pair <LL, LL>
 
int i, j, N, nr = 1;
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;
        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].y - P[i].y;
            Pante[cnt].y = P[j].x - P[i].x;
        }
    }
    sort(Pante + 1, Pante + cnt + 1, cmp());
    for (i = 2; i <= cnt; ++i) {
        if (Pante[i].x * Pante[i - 1].y == Pante[i].y * Pante[i - 1].x) ++nr;
		else {
			ANS += (nr * (nr - 1) / 2);
			nr = 1;
		}
    }
    fout << ANS + (nr * (nr - 1) / 2) << '\n';
    return 0;
}