#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#define x first
#define y second
using namespace std;

vector<pair<double,double>>sol1;
vector<pair<double,double>>sol2;
pair<double,double> v[120005];
const double EPS = 1e-12;
int n;

void solve_1()
{
    sol1.push_back({v[0].x,v[0].y});
    sol1.push_back({v[1].x,v[1].y});
    for(int i=2;i<n;i++)
    {
        int m= sol1.size();
        while((sol1[m-1].x*v[i].y-sol1[m-1].y*v[i].x)-(sol1[m-2].x*sol1[m-1].y-sol1[m-2].y*sol1[m-1].x)>EPS)
        {
            m--;
            sol1.pop_back();
        }
        sol1.push_back({v[i].x,v[i].y});
    }
}
void solve_2()
{
    sol2.push_back({v[n-1].x,v[n-1].y});
    sol2.push_back({v[n-2].x,v[n-2].y});
    for(int i=n-3;i>=0;i--)
    {
        int m=sol2.size();
        while((sol2[m-1].x*v[i].y-sol2[m-1].y*v[i].x)-(sol2[m-2].x*sol2[m-1].y-sol2[m-2].y*sol2[m-1].x)<EPS&&m>2)
        {
            m--;
            sol2.pop_back();
        }
        sol2.push_back({v[i].x,v[i].y});
    }
}
int main()
{
    ifstream f("infasuratoare.in");
    ofstream g("infasuratoare.out");
    f>>n;
    for(int i=0;i<n;i++)
    {
        double a,b;
        f>>a>>b;
        v[i]={a,b};
    }
    sort(v,v+n);
    solve_1();
    solve_2();
    g<<sol1.size()+sol2.size()-2<<"\n";
    for(int i=sol2.size()-2;i>0;i--)
        g<<fixed<<sol2[i].x<<" "<<sol2[i].y<<"\n";
    for(int i=sol1.size()-1;i>=0;i--)
        g<<fixed<<sol1[i].x<<" "<<sol1[i].y<<"\n";
    return 0;
}