// http://kmjp.hatenablog.jp/entry/2014/12/15/1000
#include <algorithm>
#include <cmath>
#include <iostream>
#include <vector>
using ll = long long;
using namespace std;
#define FOR(i, N) for (int i = 0; i < (int)(N); i++)
int N;
vector<ll> x, y;
long long count() {
  int i, j;
  ll ret = 0;
  double pi = atan(1) * 4;
  N = x.size();
  vector<double> V;
  FOR(i, N) {
    double d = atan2(y[i], x[i]);
    if (d < 0) d += 2 * pi;
    V.push_back(d);
    cerr << d << endl;
  }
  sort(V.begin(), V.end());
  FOR(i, N) for (j = i + 1; j < N; j++) {
    if (V[j] < V[i] + pi) {
      int x2 = lower_bound(V.begin(), V.end(), V[i] + pi + 1e-15) - V.begin();
      int y2 = lower_bound(V.begin(), V.end(), V[j] + pi - 1e-15) - V.begin();
      ret += max(0, y2 - x2);
      // cerr << max(0, y2 - x2) << endl;
    }
  }
  return ret;
}

int main() {
  cin >> N;
  FOR(i, N) {
    int u, v;
    cin >> u >> v;
    x.emplace_back(u);
    y.emplace_back(v);
  }
  cout << count() << endl;
}