#include<bits/stdc++.h>

using namespace std;

ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");

#define x first
#define y second

#define NMAX 120005

typedef pair<double,double> Punct;
Punct v[NMAX];
Punct s[NMAX];
int n;
int head;

void citeste()
{
    fin>>n;
    for(int i=1;i<=n;i++)
    {
        fin>>v[i].x>>v[i].y;
    }

}

int cross_product(const Punct& a,const Punct& b,const Punct& c)
{
    return (b.x-a.x)*(c.y-a.y) - (b.y-a.y)*(c.x-a.x);
}

int comp(const Punct& A,const Punct& B)
{
    return (cross_product(v[1],A,B) < 0);
}

void sorteaza()
{
    int pos = 1;
    for(int i=2;i<=n;i++)
        if(v[i] < v[pos])
            pos = i;
    swap(v[1],v[pos]);
    sort(v+2,v+n+1,comp);


}

void infasuratoare()
{
    sorteaza();

    s[1] = v[1];
    s[2] = v[2];
    head = 2;

    for(int i = 3;i <= n; ++i)
    {
        while(head >= 2 && cross_product(s[head-1], s[head], v[i]) > 0)
            --head;
        s[++head] = v[i];
    }


}

void afisare()
{
    fout<<fixed;
    fout<<head<<'\n';
    for(int i=head;i>=1;i--)
    {
        fout<<setprecision(9)<<v[i].x<<" "<<v[i].y<<'\n';
    }
}

int main()
{
    citeste();
    infasuratoare();
    afisare();
    return 0;
}