#include <algorithm>
#include <iostream>
#include <fstream>
#include <vector>
#include <iomanip>


typedef std::vector<int>::iterator iter;
#define x first
#define y second


const int MAXN = 120005;
std::ifstream f("infasuratoare.in");
std::ofstream g("infasuratoare.out");
std::pair<double, double> p[MAXN]; int n, ref = 1;
std::vector<int> ind, sol;


inline bool cmp(int a, int b)
{
	return (p[a].x - p[ref].x) * (p[b].y - p[ref].y) < (p[b].x - p[ref].x) * (p[a].y - p[ref].y);
}


bool sgn(int a, int b, int c)
{
	return (p[a].x * p[b].y + p[b].x * p[c].y + p[c].x * p[a].y - p[a].x * p[c].y - p[b].x * p[a].y - p[c].x * p[b].y > 0);
}


int main()
{
	f >> n;
	for (int i = 1; i <= n; i++) {
		f >> p[i].x >> p[i].y;
		
		if (p[ref] > p[i]) {
			ref = i;
		}
	}
	std::cout << p[ref].x << ' ' << p[ref].y << std::endl << std::endl;

	for (int i = 1; i <= n; i++) {
		if (p[i] != p[ref]) {
			ind.push_back(i);
		}
	}


	std::sort(ind.begin(), ind.end(), cmp);
	for (int i = 0; i < ind.size(); i++) {
		std::cout << p[ind[i]].x << ' ' << p[ind[i]].y << std::endl;
	}


	for (iter it = ind.begin(); it != ind.end(); it++) {
		while (sol.size() > 1 && sgn(*(sol.end() - 2), *(sol.end() - 1), *it)) {
			sol.pop_back();
		}
		sol.push_back(*it);
	}
	sol.push_back(ref);

	reverse(sol.begin(), sol.end());

	g << sol.size() << '\n';
	for (iter it = sol.begin(); it != sol.end(); it++) {
		g << std::setprecision(32) << p[*it].first << ' ' << p[*it].second << '\n';
	}



	//system("pause");
	f.close();
	g.close();
	return 0;
}