#include <fstream>
#include <algorithm>
#include <iomanip>

using namespace std;

ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");

struct punct {double x; double y;}s[120005],p[120005];
int n,i,j,k;

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

bool conditie(punct a, punct b)
{
    double d;
    d=determinant(a,b,p[1]);
    if (d>0) return true;
    else return false;
}

int main()
{
    f>>n;
    f>>p[1].x>>p[1].y;
    j=1;
    for(i=2;i<=n;i++)
    {
        f>>p[i].x>>p[i].y;
        if(p[i].x<p[j].x || ((p[i].x==p[j].x) && (p[i].y<p[j].y)))
            j=i;
    }
    swap(p[1],p[j]);
    sort(p+2,p+n+1,conditie);

    s[1]=p[1]; s[2]=p[2];
    k=2;
    for(i=3;i<=n;i++)
    {
        if(determinant(s[k-1],s[k],p[i])<0)k--;
        s[++k]=p[i];
    }

    g<<k<<'\n';
    g<<fixed;
    for(i=1;i<=k;i++)
    {
        g<<setprecision(6)<<s[i].x<<' '<<s[i].y<<'\n';
    }

    return 0;
}