#include <bits/stdc++.h>
 
using namespace std;
 
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
 
int n,i,m;
struct p{ double x, y;} puncte[120001],top[120001];
 
double area(p a, p b,p c)
{
  return a.x*b.y+b.x*c.y+a.y+c.x-c.x*b.y-b.x*a.y-c.y*a.x;
}
 
bool comparator(p a, p b)
{
  return area(puncte[1], a, b)>=0;
}
 
int main()
{
  m=1;
  fin>>n;
  for (i=1;i<=n;i++)
  {
    fin>>puncte[i].x>>puncte[i].y;
    if (puncte[m].x<puncte[i].x)
      m=i;
    else if (puncte[i].x==puncte[m].x&&puncte[i].y<puncte[m].y)
      m=i;
  }
  swap(puncte[1],puncte[m]);
  sort(puncte+2, puncte+n+1, comparator);
  int x=0;
  for (i=1;i<=n;i++)
  {
    while (x>1&&area(top[x-1],top[x],puncte[i])<0) x--;
    top[++x]=puncte[i];
  }
  fout<<x<<endl;
  for (int i=1;i<=x;i++)
    fout<<fixed<<top[i].x<<' '<<top[i].y<<'\n';
  return 0;
}