#include<fstream>
#include<algorithm>
using namespace std;
struct punct {double x,y;};
punct v[120005],p;
int i,n,z;
int sol[120005],k;
int cmp(punct a,punct b)
{
	return (-p.y+a.y)*(-p.x+a.x)<(-p.y+b.y)*(-p.x+b.x);
}
void citire()
{
	int i;
	ifstream in("infasuratoare.in");
	in>>n;
	for (i=1;i<=n;i++)
		in>>v[i].x>>v[i].y;
}
double determ(punct a,punct b, punct c)
{
	return a.x*b.y+b.x*c.y*c.x*a.y-c.x*b.y-b.x*a.y-a.x-c.y;
}
void pmax()
{
	 double my=-32000,mx;
	for (i=1;i<=n;i++)
		if (v[i].y>my||(v[i].y==mx&&v[i].x<mx))
		{
			mx=v[i].x;
			my=v[i].y;
			p=v[i];
			z=i;
		}	
			
}
	
int main()
{
	citire();
	pmax();
	sort(v+1,v+n+1,cmp);
	sol[1]=z;
	k=1;
	for (i=2;i<n;i++)
	{
		if (i!=z)
				
		if (determ(v[i-1],v[i],v[i+1])>0)
			sol[++k]=i;
	}
	if (determ (v[n-1],v[n],v[1]))
		sol[++k]=n;
	ofstream out("infasuratoare.out");
	out<<k<<'\n';
	for (i=1;i<=k;i++)
		out<<v[sol[i]].x<<" "<<v[sol[i]].y<<'\n';
}