#include <iostream>
#include<fstream>
#include<algorithm>
using namespace std;

ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");
struct punct
{
    double x,y;
};


int n,i,k;
punct sir[120002], s[120002];

double determinant( punct a,punct b,punct c)
{
    return a.x*b.y + b.x*c.y + a.y*c.x - c.x*b.y - b.x*a.y - c.y*a.x;
}

bool cmp(punct P1,punct P2)
{
    return determinant(sir[1],P1,P2)>=0;
}

int main()
{
    f>>n;
    k=1;
    for(i=1;i<=n;++i)
    {
        f>>sir[i].x>>sir[i].y;
        if(sir[i].x>sir[k].x) k=i;
        else
            if(sir[i].x==sir[k].x && sir[i].y<sir[k].y) k=i;
    }
    swap(sir[1],sir[k]);
    sort(sir+2,sir+n+1,cmp);
     int dr=0;
    for (int i=1; i<=n; i++)
    {
        while (dr>1 &&  determinant(s[dr-1],s[dr],sir[i]) < 0) dr--;
        dr++;
        s[dr]=sir[i];
    }

    g<<dr<<'\n';
    for (int i=1; i<=dr; i++)
        g<<fixed<<s[i].x<<' '<<s[i].y<<'\n';
     f.close();
     g.close();
    return 0;
}