#include <iostream>
#include <algorithm>
#include <cmath>
#include <map>
#define int long long
#define double long double
using namespace std;
const int N = 2e3+10;
int n, p, ans;
struct Point {
    int x, y;
    double angle[2];
    bool operator<(const Point &b) const {
        return x == b.x ? y < b.y : x < b.x;
    }
} list[N], stk[N], inside[N];
map<Point, bool> mp;
int cross(Point p0, Point p1, Point p2) {
    return (p1.x - p0.x) * (p2.y - p0.y) - (p2.x - p0.x) * (p1.y - p0.y);
}
bool cmp(Point a, Point b) {
    if (a.x != b.x) return a.x < b.x;
    return a.y < b.y;
}
 
int dis(Point a, Point b) {
    return (b.x - a.x) * (b.x - a.x) + (b.y - a.y) * (b.y - a.y);
}
double cos(Point a, Point b, Point c) {
    // cos value of angle abc
    // ac^2 = ab^2 + bc^2 - 2ab * bc * cos(abc)
    // cos(abc) = (ab^2 + bc^2 - ac^2) / 2ab * bc
    return (dis(a, b) + dis(b, c) - dis(a, c)) / (2 * sqrtl(dis(a, b)) * sqrtl(dis(b, c)));
}
void andrew() {
    p = 1;
    stk[0] = list[0], stk[1] = list[1];
    for (int i = 2; i < n; ++i) {
        while (p > 0 && cross(stk[p - 1], stk[p], list[i]) <= 0) --p;
        stk[++p] = list[i];
    }
    stk[++p] = list[n - 2];
    for (int i = n - 3; i >= 0; --i) {
        while (p > 0 && cross(stk[p - 1], stk[p], list[i]) <= 0) --p;
        stk[++p] = list[i];
    }
}
signed main(){
    ios::sync_with_stdio(0);
    cin >> n;
    for (int i = 0; i < n; ++i) cin >> list[i].x >> list[i].y;
    sort(list, list + n, cmp);
    andrew();
    // for (int i = 0; i < p; ++i) {
    //     cout << stk[i].x << " " << stk[i].y << endl;
    // }
    for (int i = 0; i < p; ++i) {
        mp[stk[i]] = true;
    }
    int idx = 0;
    for (int i = 0; i < n; ++i) {
        if (mp[list[i]] == false) {
            inside[idx++] = list[i];
        }
    }
    // for (int i = 0; i < n; ++i) {   // for each point
    //     for (int j = 0; j < p; ++j) {   // for each edge
    //         if (list[i] == stk[j]) {
    //             list[i].inside = false;
    //             break;
    //         }
    //         list[i].angle[j][0] = cos(list[i], stk[j], stk[j + 1]);
    //         list[i].angle[j][1] = cos(list[i], stk[j + 1], stk[j]);
    //     }
    //     // if (!list[i].inside) {
    //     //     for (int j = 0; j < p; ++j) {
    //     //         list[i].angle[j][0] = 1;
    //     //         list[i].angle[j][1] = 1;
    //     //     }
    //     // }
    // }
    for (int i = 0; i < p; ++i) {
        for (int j = 0; j < idx; ++j) {
            inside[j].angle[0] = cos(inside[j], stk[i], stk[i + 1]);
            inside[j].angle[1] = cos(inside[j], stk[i + 1], stk[i]);
        }
        sort(inside, inside + idx, [&](Point a, Point b){
            return a.angle[0] > b.angle[0];
        });
        double angle2 = 1;
        for (int j = 0; j < idx; ++j) {
            if (j == 0) {
                angle2 = inside[j].angle[1];
                ans++;
            }
            else {
                if (inside[j].angle[1] > angle2) {
                    ans++;
                }
            }
        }
    }
    cout << ans + 1 << endl;
    return 0;
}