#include <bits/stdc++.h>
using namespace std;
int x[2123], y[2123];
int main() {
  int n, ans = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    scanf("%d%d", &x[i], &y[i]);
  }
  for (int i = 1; i <= n - 2; i++) {
    for (int j = i + 1; j <= n - 1; j++) {
      for (int k = j + 1; k <= n; k++) {
        ans += (((y[k] - y[i]) * (x[j] - x[i])) !=
                ((y[j] - y[i]) * (x[k] - x[i])));
      }
    }
  }
  cout << ans << endl;
  return 0;
}
