#include <iostream>
#include <fstream>
#include <algorithm>
#include <iomanip>
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");

struct puncte{
double x,y;
}v[105],q[105];

double produs(puncte a,puncte b,puncte c)
{
    return (b.x-a.x)*(c.y-a.y)-(c.x-a.x)*(b.y-a.y);
}

bool cmp(puncte b,puncte c)
{
    return produs(v[1],b,c)<0;
}

int n,i,poz,vf;

int main()
{
    f>>n;
    for(i=1;i<=n;i++)
    {
        f>>v[i].x>>v[i].y;
    }
    poz=1;
    for(i=2;i<=n;i++)
    {
        if(v[i].x<v[poz].x||(v[i].x==v[poz].x&&v[i].y<v[poz].y))
            poz=i;
    }
    swap(v[poz],v[1]);
    sort(v+2,v+n+1,cmp);
    vf=2;
    q[1]=v[1];
    q[2]=v[2];
    for(i=3;i<=n;i++)
    {
        while(vf>=2&&produs(q[vf-1],q[vf],v[i])>0)
            {
            vf--;

            }
        vf++;
        q[vf]=v[i];
    }
    g<<vf<<'\n';
    g<<q[1].x<<" "<<q[1].y<<'\n';
    for(i=vf;i>=1;i--)
        g<<q[i].x<<" "<<q[i].y<<'\n';;

    return 0;
}