#include <iostream>
#include <fstream>
#include <vector>
#include <random>
#include <algorithm>
#include <queue>
#include <string.h>
using namespace std;

typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<pair<int,int>> VII;

template<class A, class B> 
ostream& operator<<(ostream& os, pair<A,B> &p) {
    os << "(" << p.first << ", " << p.second << ")";
    return os;
}

template<typename T>
void print(vector<T> sez) {
    for (T x : sez) cout << x << " ";
    cout << endl;
}

PII operator-(PII a, PII b) {
    return {a.first-b.first, a.second-b.second};
}

int cross(PII a, PII b) {
    return a.first*b.second - a.second*b.first;
}

vector<PII> graham_scan(vector<PII> points) {
    int n=points.size();
    PII t=*min_element(points.begin(), points.end());
    
    vector<pair<double, PII>> angles;
    for (PII p : points) if (p!=t) {
        PII v=p-t;  // t->p
        double a=atan2(v.second, v.first);
        angles.push_back({a, p});
    }
    sort(angles.begin(),angles.end());

    vector<PII> hull = {t};
    for (auto [_, p] : angles) {  // doda novo tocko
        while (hull.size()>=2) {  // popravi konveksnost
            PII a=hull[hull.size()-2], b=hull[hull.size()-1];
            PII ab=b-a, ap=p-a;
            if (cross(ab, ap) > 0) break;
            hull.pop_back();
        }
        hull.push_back(p);
    }
    return hull;
}

int main() {
    vector<PII> points = {{4,0}, {2,3}, {5,2}, {6,1}, {8,4}, {6,6}, {5,4}, {4,5}, {2,6}, {1,1}, {1,5}, {3,2}};
    auto hull = graham_scan(points);
    print(hull);
    return 0;
}