#include <bits/stdc++.h>
using namespace std;
struct point {
  int x, y;
};
struct Vector {
  int vx, vy, x, y;
};
vector<Vector> line;
int main() {
  int n, sum = 0, num = 0;
  scanf("%d", &n);
  point p[55];
  Vector v[2505];
  for (int i = 1; i <= n; ++i) scanf("%d%d", &p[i].x, &p[i].y);
  for (int i = 1; i < n; ++i) {
    for (int j = i + 1; j <= n; ++j) {
      int a, b, c, d, e = 0;
      a = p[i].x - p[j].x;
      b = p[i].y - p[j].y;
      for (int k = 0; k < line.size(); ++k) {
        if (a * line[k].vy == b * line[k].vx) {
          c = p[i].x - line[k].x;
          d = p[i].y - line[k].y;
          if (c * b == a * d) {
            e = -1;
            break;
          } else
            continue;
        } else
          e++;
      }
      if (e >= 0) {
        line.push_back({a, b, p[i].x, p[i].y});
        sum += e;
      }
    }
  }
  printf("%d\n", sum);
}
