#include <fstream>
#include <algorithm>
#include <iomanip>
#define NMax 120005
using namespace std;
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
struct Punct
{
  double x, y;
};
Punct P[NMax],S[NMax];
int N,k;
inline double Area(Punct A, Punct B, Punct C)
{
    return (A.x*B.y+B.x*C.y+C.x*A.y-A.y*B.x-B.y*C.x-C.y*A.x);
}
inline int cmp(Punct A,Punct B)
{
    if(Area(P[1],A,B)>0)
        return 1;
    return 0;
}
void Read()
{
    fin>>N;
    for(int i=1;i<=N;i++)
        {
            fin>>P[i].x>>P[i].y;
        }
    int Min=1;
    for(int i=2;i<=N;i++)
        {
            if(P[i].y<P[Min].y ||(P[i].y==P[Min].y && P[i].x<P[Min].x))
                Min=i;
        }
    swap(P[1],P[Min]);
    sort(P+2,P+N+1,cmp);
}
void Solve()
{
    S[1]=P[1];
    S[2]=P[2];
    k=2;
    for(int i=3;i<=N;i++)
        {
            while(k>=2&& Area(S[k-1],S[k],P[i])<0)
                k--;
            S[++k]=P[i];
        }
}
void Print()
{
    fout<<k<<"\n";
    for(int i=1;i<=k;i++)
        fout<<fixed<<setprecision(9)<<S[i].x<<" "<<S[i].y<<"\n";
}
int main()
{
    Read();
    Solve();
    Print();
    return 0;
}