#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int, int> P;

signed main() {
    int n; cin >> n;
    vector<P> xy;
    
    for (int i=0; i<n; i++) {
        int xi, yi; cin >> xi >> yi;
        xy.push_back(P(xi, yi));
    }
    
    sort(xy.begin(), xy.end(), [](auto const& lhs, auto const& rhs){return lhs.first<rhs.first;});
    int ans = 0;
    
    for (int i=0; i<n; i++) {
        for (int j=i+1; j<n; j++) {
            for (int k=j+1; k<n; k++) {
                int x1=xy[i].first, y1=xy[i].second;
                int x2=xy[j].first, y2=xy[j].second;
                int x3=xy[k].first, y3=xy[k].second;
                
                if (x1==x2 && x2==x3) {
                    continue;
                }
                else if (x1==x2) {
                    if ((x1*y3-y1*x3>0 && x2*y3-y2*x3<0) || (x1*y3-y1*x3<0 && x2*y3-y2*x3>0)) {
                        ans++;
                    }
                }
                else if (x2==x3) {
                    if ((x2*y1-y2*x1>0 && x3*y1-y3*x1<0) || (x2*y1-y2*x1<0 && x3*y1-y3*x1>0)) {
                        ans++;
                    }
                }
                else {
                    if ((x1*y2-y1*x2<0 && x2*y3-y2*x3<0 && x1*y3-y1*x3>0) || (x1*y2-y1*x2>0 && x2*y3-y2*x3>0 && x1*y3-y1*x3<0)) {
                        ans++;
                    }
                }
            }
        }
    }
    
    cout << ans << endl;
}