#include <fstream>
#include <cmath>
#include <algorithm>
#include <iomanip>
using namespace std;
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
 
struct point
{
    double x,y;
    bool u;
}v[120001];
 
int n,i,k,p,sol[120001],s[120001],t,j;
double eps=1e-12;
 
bool cmp (point A, point B)
{
    if (fabs(A.y-B.y)<=eps) return (A.x<B.x);
    return (A.y<B.y);
}
 
bool det (point A,point B,point C)
{
    return ((long double )B.x-A.x)*(C.y-A.y)-(C.x-A.x)*(B.y-A.y)>0;
}
 
int main ()
{
    fin>>n;
    for (i=1;i<=n;i++) fin>>v[i].x>>v[i].y;
    sort (v+1,v+n+1,cmp);
    k=0;p=1;
    for (i=1;i>0;i=i+p)
    {
        if (v[i].u==1) continue;
        s[++k]=i; v[i].u=1;
        if (k<3) continue;
        while (k>2&&det(v[s[k]],v[s[k-1]],v[s[k-2]]))
        {
            v[s[k-1]].u=0;
            s[k-1]=s[k];
            k--;
        }
        if (i==n) 
        {
            p=-1;
            for (j=1;j<=k;j++) sol[j]=s[j];
            t=k;
            k=1;
            s[k]=n;
        }
    }
    for (i=2;i<=k;i++) sol[t-1+i]=s[i];
    t=t+k-1;
    fout<<t<<"\n";
    for (i=1;i<=t;i++) fout<<fixed<<v[sol[i]].x<<" "<<v[sol[i]].y<<"\n";
}