#include<fstream>
#include<algorithm>
#include<vector>
#define NMAX 120005
#define x second
#define y first
#define TYPE pair <double,double>
#define L s.size()
using namespace std;
int n;
vector<int> s;
TYPE v[NMAX];
void read()
{
	ifstream fin("infasuratoare.in");
	fin>>n;
	for(int i=1;i<=n;i++)
		fin>>v[i].x>>v[i].y;
	fin.close();
}
void print()
{
	ofstream fout("infasuratoare.out");
	fout<<L<<'\n';
	for(int i=L;i;i--)
		fout<<fixed<<v[s[i-1]].x<<' '<<v[s[i-1]].y<<'\n';
	fout.close();
}
inline double area(TYPE a,TYPE b,TYPE c)
{
	return 	a.x * b.y + b.x * c.y + c.x * a.y -
			b.x * a.y - c.x * b.y - a.x * c.y;
}
inline bool cmp(TYPE a,TYPE b)
{
	return (area(v[1],a,b)<0);
}
void solve()
{
	int poz=1;
	for(int i=2;i<=n;i++)
		if(v[i]<v[poz])
			poz=i;
	swap(v[1],v[poz]);
	sort(v+2,v+n+1,cmp);
	s.push_back(1);
	s.push_back(2);
	for(int i=3;i<=n;i++)
	{
		while(L>=1 && area(v[s[L-2]],v[s[L-1]],v[i])>0)
			s.pop_back();
		s.push_back(i);
	}
}
int main()
{
	read();
	solve();
	print();
	return 0;
}