#include<fstream>
#include<algorithm>
using namespace std;
int n, m, i, nr, j, ii, jj, c1, c2, nr1;
long long d;
pair<int, int> p[1002];
struct dr{
   int x;
   int y;
};
dr v[1000000];
ifstream fin("trapez.in");
ofstream fout("trapez.out");
long long det(int X1, int Y1, int X2, int Y2, int X3, int Y3){
    return (X3 - X1) * 1LL * (Y2 - Y1) - (X2 - X1) * 1LL * (Y3 - Y1);
}
int cadran(dr a){
   if(a.y > 0){
       return 1;
   }
   return 2;
}
int cmp(dr a, dr b){
    int c1 = cadran(a);
    int c2 = cadran(b);
    if(c1 == c2){
        int d = det(0, 0, a.x, a.y, b.x, b.y);
        return d < 0;
    }
    return c1 < c2;
}
int main(){
    fin>> n;
    for(i = 1; i <= n; i++){
        fin>> p[i].first >> p[i].second;
    }
    for(i = 1; i < n; i++){
        for(j = i + 1; j <= n; j++){
            m++;
            ii = i;
            jj = j;
            if(p[ii].first > p[jj].first){
                swap(ii, jj);
            }
            v[m].x = p[jj].first - p[ii].first;
            v[m].y = p[jj].second - p[ii].second;
        }
    }
    sort(v + 1, v + m + 1, cmp);
    for(i = 1; i < m; i++){
        c1 = cadran(v[i]);
        c2 = cadran(v[i+1]);
        if(c1 == c2){
            d = det(0, 0, v[i].x, v[i].y, v[i+1].x, v[i+1].y);
            if(d == 0){
                nr1++;
            }
            else{
                nr += (nr1) * (nr1+1) / 2;
                nr1 = 0;
            }
        }
        else{
            nr += (nr1) * (nr1+1) / 2;
            nr1 = 0;
        }
    }
    nr += nr1 * (nr1 + 1) / 2;
    fout<< nr <<"\n";
    return 0;
}