#include <fstream>

using namespace std;

ifstream cin("infasuratoare.in");
ofstream cout("infasuratoare.out");

struct p
{
    float x, y;
}v[120000], dreapta[120000], stanga[120000], st[120000];

int n;

void sortare()
{
    for(int i=1;i<=n;i++){
        for(int j=i+1;j<=n;++j)
        if(v[i].y>v[j].y){
            v[0]=v[i];
            v[i]=v[j];
            v[j]=v[0];
        }
        else if(v[i].y==v[j].y)
        {
            if(v[i].x>v[j].x){
            v[0]=v[i];
            v[i]=v[j];
            v[j]=v[0];
            }
        }
    }
}

int main()
{
    int arie;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>v[i].x>>v[i].y;
    }
    sortare();
    int nr1=2, nr2=2;
    dreapta[1]=v[1];
    stanga[1]=v[1];
    for(int i=2;i<n;i++)
    {
        float arie=v[1].x*v[n].y + v[n].x*v[i].y + v[i].x*v[1].y - v[i].x*v[n].y - v[1].x*v[i].y - v[n].x*v[1].y;
        if(arie<0)
        {
            dreapta[nr1]=v[i];
            nr1++;
        }
        else
        {
            stanga[nr2]=v[i];
            nr2++;
        }
    }
    dreapta[nr1]=v[n];
    stanga[nr2]=v[n];
    ///dreapta
    st[1]=dreapta[1];
    st[2]=dreapta[2];
    int k=2;
    for(int i=3;i<=nr1;i++)
    {
        arie=st[k-1].x*st[k].y + st[k].x*dreapta[i].y + dreapta[i].x*st[k-1].y - dreapta[i].x*st[k].y - st[k-1].x*dreapta[i].y - st[k].x*st[k-1].y;
        while(arie<0 && k>1)
        {
            k--;
            arie=st[k-1].x*st[k].y + st[k].x*dreapta[i].y + dreapta[i].x*st[k-1].y - dreapta[i].x*st[k].y - st[k-1].x*dreapta[i].y - st[k].x*st[k-1].y;
        }
        k++;
        st[k]=dreapta[i];
    }
    for(int i=1;i<=k;i++)
    {
        cout<<st[i].x<<" "<<st[i].y<<'\n';
    }
    ///stanga
    /*for(int i=1;i<=nr2;i++)
    {
        cout<<stanga[i].x<<" "<<stanga[i].y<<'\n';
    }*/
    st[1]=stanga[1];
    st[2]=stanga[2];
    k=2;
    for(int i=3;i<=nr2;i++)
    {
        arie=st[k-1].x*st[k].y + st[k].x*stanga[i].y + stanga[i].x*st[k-1].y - stanga[i].x*st[k].y - st[k-1].x*stanga[i].y - st[k].x*st[k-1].y;
        while(arie>0 && k>1)
        {
            k--;
            arie=st[k-1].x*st[k].y + st[k].x*stanga[i].y + stanga[i].x*st[k-1].y - stanga[i].x*st[k].y - st[k-1].x*stanga[i].y - st[k].x*st[k-1].y;
        }
        k++;
        st[k]=stanga[i];
    }
    for(int i=k-1;i>=2;i--)
    {
        cout<<st[i].x<<" "<<st[i].y<<'\n';
    }
    return 0;
}