#include<fstream>
#include<math.h>
#include<algorithm>
#include<iomanip>
using namespace std;

struct punct{
    double x,y,d;
};

punct p[120000],p0,s[120000];

 double prod(punct A,punct B,punct C)
    {
    return A.x*B.y+B.x*C.y+C.x*A.y-B.y*C.x-C.y*A.x-A.y*B.x;
    }

 int compara ( punct A,punct B)
 {
     double pr=prod(p[1],B,A);
    if(pr<0)return 1;
    if(pr==0&&A.d>B.d)return 1;
    return 0;
    }
long i,n,k,j,ps;
double pr;

inline void sch(punct &q,punct &w)
{
    punct aux;
    aux=q;q=w;w=aux;
}
 void cauta_primul()
{   long i,im;
    im=1;
    for (i=2;i<=n;i++)
        if (p[i].y<p[im].y) im=i;
            else if (p[i].y==p[im].y && p[i].x<p[im].x) im=i;
     sch(p[1],p[im]);
}
double dist(punct A, punct B)
{
    double u,v;
    u=A.x-B.x;
    v=A.y-B.y;
    return sqrt(u*u+v*v);
}

int main()
{long i,m;
    ifstream f("infasuratoare.in");
    ofstream g("infasuratoare.out");
    f>>n;
    for (i=1;i<=n;++i) f>>p[i].x>>p[i].y;
    cauta_primul();
    p0=p[1];
    for (i=2;i<=n;i++) p[i].d=dist(p0,p[i]);

    sort(p+2,p+n+1,compara);

    i=1;
    s[1]=p[1];
    s[2]=p[2];
    m=2;
    for (j=3;j<=n;++j)
        if (prod(p0,p[j-1],p[j])>0){++m;s[m]=p[j];}


    for (j=1;j<=m;++j) p[j]=s[j];
    n=m;
    ps=3;
    for (i=4;i<=n;++i)
    {
        do{
            pr=prod(s[ps-1],s[ps],p[i]);
            if (pr<0) --ps;
        }while(pr<0);
        s[++ps]=p[i];
    }
    g<<ps<<"\n";
    for (i=1;i<=ps;++i)
        g<<fixed<<s[i].x<<' '<<s[i].y<<"\n";
 return 0;
}