#include<stdio.h>
#include<fstream.h>
#include<iomanip.h>

using namespace std;

double x[125000],y[125000];
long a[125000],sol[125000],cont,mi;

void qs(long i, long j)
{
	long s=i,d=j,aux,piv=((i+j)>>1);
	while(s<=d)
	{
		while((y[a[s]]-y[mi])*(x[a[piv]]-x[mi])<(y[a[piv]]-y[mi])*(x[a[s]]-x[mi]))s++;
		while((y[a[d]]-y[mi])*(x[a[piv]]-x[mi])>(y[a[piv]]-y[mi])*(x[a[d]]-x[mi]))d--;
		if(s<=d)
		{
			aux=a[s];
			a[s]=a[d];
			a[d]=aux;
			d--;
			s++;
		}
	}
	if(i<d)qs(i,d);
	if(s<j)qs(s,j);
}
	
int det(long i1, long i2, long i3)
{
	if(x[i1]*y[i2]+x[i2]*y[i3]+x[i3]*y[i1]>y[i1]*x[i2]+y[i2]*x[i3]+y[i3]*x[i1]) return 1;
	else return 0;
}
	
int main()
{ 
	long n,i,j,gasit,k,temp;
	ifstream f("infasuratoare.in");
	ofstream g("infasuratoare.out");
	f>>n>>x[1]>>y[1];
	mi=1;
	for(i=2;i<=n;i++)
	{
		f>>x[i]>>y[i];
		if(x[i]<x[mi])mi=i;
		else if(x[i]==x[mi])if(y[i]<y[mi])mi=i;
	}
    a[n]=mi;
	for(i=1;i<mi;i++)a[i]=i;
	a[mi]=n;
	for(i=mi+1;i<n;i++)a[i]=i;
	qs(1,n-1);
	gasit=a[n];
	for(i=n;i>=2;i--)a[i]=a[i-1];
	a[1]=gasit;
	a[n+1]=a[1];
	sol[1]=a[1];
	sol[2]=a[2];
	i=2;j=3;
	while(j<=n)
	{
		gasit=0;
		for(k=2;k<=i&&!gasit;k++)if(!det(sol[k-1],sol[k],a[j])){gasit=1;temp=k;}
		if(!gasit)
		{
			sol[++i]=a[j];
			j++;
		}
		else
		{
			i=temp;
			sol[i]=a[j];
			j++;
		}
	}
	/*FILE *g=fopen("infasuratoare.out","w");
	fprintf(g,"%d\n",i);
	for(j=1;j<=i;j++)fprintf(g,"%.6lf %.6lf\n",x[sol[j]],y[sol[j]]);*/
	g<<i<<'\n';
	for(j=1;j<=i;j++)g<<fixed<<setprecision(6)<<x[sol[j]]<<' '<<y[sol[j]]<<'\n';
	return 0;
}