#include <bits/stdc++.h>
using namespace std;
const int NMAX = 1000;

struct fractie {
    int a, b; // a / b
};

fractie v[NMAX * NMAX];

bool cmp(fractie x, fractie y) {
    long long p1, p2;
    p1 = (long long) x.a * y.b;
    p2 = (long long) x.b * y.a;
    return p1 <= p2;
}

bool isEqual(fractie x, fractie y) {
    long long p1, p2;
    p1 = (long long) x.a * y.b;
    p2 = (long long) x.b * y.a;
    return p1 == p2;
}

int coordX[NMAX], coordY[NMAX];

int main() {
    int n, i, j, pantaInf, trapez, pante, nr;
    fractie p;
    FILE *fin, *fout;

    fin = fopen("trapez.in", "r");
    fscanf(fin, "%d", &n);
    for(i = 0; i < n; i++)
        fscanf(fin, "%d%d", &coordX[i], &coordY[i]);
    fclose(fin);
    pantaInf = 0;
    pante = 0;
    for(i = 0; i < n; i++) {
        for(j = i + 1; j < n; j++) {
            v[pante].a = coordY[j] - coordY[i];
            v[pante].b = coordX[j] - coordX[i];
            pante++;
        }
    }
    sort(v, v + pante, cmp);
    //cout << "pantaInf = " << pantaInf << endl;
    trapez = 0;
    i = 0;
    while(i < pante) {
        nr = 0;
        p = v[i];
        while(i < pante && isEqual(v[i], p)) {
            nr++;
            i++;
        }
        //cout << "nr = " << nr << endl;
        trapez += nr * (nr - 1) / 2;
        //i++;
    }

    fout = fopen("trapez.out", "w");
    fprintf(fout, "%d", trapez);
    fclose(fout);

    return 0;
}