#include <bits/stdc++.h>
#define all(a) (a).begin(), (a).end()
#define sz(a) (int) (a).size()
#define forn(i, n) for(int i = 0; i < (n); i++)
#define int long long
using namespace std;

typedef long long ll;
typedef long double LD;
struct P{
    int x, y, id;
    bool operator< (P p) const { return tie(x, y) < tie(p.x, p.y); }
    bool operator== (const P& o) const { return x == o.x && y == o.y; }
    P operator+ (P p) const { return {x + p.x, y + p.y}; }
    P operator- (P p) const { return {x - p.x, y - p.y}; }
    int cross(P p) const { return x * p.y - y * p.x; }
    int dot(P p) const { return x * p.x + y * p.y; }
    int cross(P a, P b) const { return (a - *this).cross(b - *this); }
    int dist2() const { return x * x + y * y; }
    LD dist() const { return sqrt((LD) dist2()); }
};

vector<P> convexHull(vector<P> pts) {
    if(sz(pts) <= 1) return pts;
    sort(all(pts));
    vector<P> h(sz(pts)+1);
    int s = 0, t = 0;
    for (int it = 2; it--; s = --t, reverse(all(pts)))
        for (P p : pts) {
            while(t >= s + 2 && h[t - 2].cross(h[t - 1], p) <= 0) t--;
            h[t++] = p;
        }
    return {h.begin(), h.begin() + t - (t == 2 && h[0] == h[1])};
}

const int N = 2e3 + 11;
bool not_in[N];

LD angle(P a, P b, P c){
    return abs((a - b).dot(b - c) / (a - b).dist() / (b - c).dist());
}

void solve(){
    int n; cin >> n;
    vector<P> a;
    for(int i = 0; i < n; i++){
        int x, y; cin >> x >> y;
        a.push_back({x, y, i});
    }
    vector<P> C = convexHull(a);
    for(auto [x, y, id] : C){
        not_in[id] = true;
    }
    vector<int> in;
    for(int i = 0; i < n; i++){
        if(!not_in[i]) in.push_back(i);
    }

    int ans = 1;
    for(int i = 0; i < sz(C); i++){
        P A = C[i], B = C[(i + 1) % sz(C)];
        vector<pair<LD, LD>> angles;
        for(auto x : in){
            angles.push_back({angle(A, B, a[x]), angle(B, A, a[x])});
        }
        sort(angles.begin(), angles.end());
        LD cur_min = 1 << 30;
        for(auto [x, y] : angles){
            if(y < cur_min)
                ans++;
            cur_min = min(cur_min, y);
        }
    }
    cout << ans << '\n';
}

int32_t main(){
    cin.tie(0)->sync_with_stdio(false);
    int t = 1; // cin >> t;
    while(t--){
        solve();
    }
}