#include<fstream>
#include<algorithm>
using namespace std;
int s[101],i,n,det,viz[101];
ifstream f("infasuratoareconvexa.in");
ofstream g("infasuratoareconvexa.out");

struct punct
{
	int x,y;
}v[101];



int determinant(punct A,punct B,punct C)
{
	return (B.x-A.x)*(C.y-A.y)-(C.x-A.x)*(B.y-A.y);
}

bool cmp(punct a,punct b)
{
	if(a.x==b.x)return a.y<b.y;
	return a.x<b.x;
}


int main()
{
	f>>n;
	for(i=1;i<=n;i++)
		f>>v[i].x>>v[i].y;
	int min=1;
	for(i=2;i<=n;i++)
		if(v[i].x<v[min].x || v[i].x==v[min].x && v[i].y<v[min].y)min=i;
	punct temp=v[1];
	v[1]=v[min];
	v[min]=temp;
	sort(v+2,v+n+1,cmp);
	for(i=2;i<=n;i++)
		if(v[i-1].x==v[i].x&&v[i-1].y==v[i].y)
		{
			for(int j=i;j<=n;j++)
				v[j-1]=v[j];
			i--;
			n--;
		}
	s[1]=1;s[2]=2;viz[2]=1;
	int k=2;
	for(i=3;i<=n;i++)
	{
		while(determinant(v[s[k-1]],v[s[k]],v[i])<0  && k>1)
		{
			viz[s[k]]=0;s[k]=0;k--;
		}
		
		s[++k]=i;
		viz[i]=1;
	}
	for(i=n-1;i>=1;i--)
	{
		if(!viz[i])
		while(determinant(v[s[k-1]],v[s[k]],v[i])<0&&k>1)
		{
			viz[s[k]]=0;s[k]=0;k--;
		}
		s[++k]=i;
		viz[i]=1;
	}
	g<<k-1<<"\n";
	//for(i=k;i>1;i--)
	for(i=1;i<k;i++)
		g<<v[s[i]].x<<" "<<v[s[i]].y<<"\n";
	return 0;
}