#include <iostream>
#include <fstream>
#include <algorithm>
#include <iomanip>
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");
struct punct
{
    double x,y;
};
punct v[120001],stiva[120001];
int n,poz,varf;
inline double ceas_trig(const punct &P0,const punct &P1,const punct &P2)
{
    return (P1.x-P0.x)*(P2.y-P0.y)-(P2.x-P0.x)*(P1.y-P0.y);
}
inline int cmp(const punct &P1,const punct &P2)
{
    return ceas_trig(v[1],P1,P2) < 0;
}
int main()
{
    int i;
    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)
        {
            poz=i;
        }
        else
        {
            if(v[i].x==v[poz].x && v[i].y<v[poz].y)
            {
                poz=i;
            }
        }
    }
    swap(v[1],v[poz]);
    sort(v+2,v+n+1,cmp);
    stiva[1]=v[1];
    stiva[2]=v[2];
    varf=2;
    for(i=3;i<=n;i++)
    {
        while(varf>=2 && ceas_trig(stiva[varf-1],stiva[varf],v[i])>0)
        {
            varf--;
        }
        varf++;
        stiva[varf]=v[i];
    }
    g<<varf<<"\n";
    for(i=varf;i>=1;i--)
    {
        g<<fixed<<setprecision(9)<<stiva[i].x<<" "<<stiva[i].y<<"\n";
    }
    return 0;
}