#include <bits/stdc++.h>

using namespace std;

ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");

int n,i,m;
struct p{ double x, y;} puncte[120001],top[120001];

double area(p a, p b,p 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 comparator(p a, p b)
{
    return area(puncte[i], a, b)>=0;
}

int main()
{
    m=1;
    fin>>n;
    for (i=1;i<=n;i++)
    {
        fin>>puncte[i].x>>puncte[i].y;
        if (puncte[m].x<puncte[i].x)
            m=i;
        else if (puncte[i].x==puncte[m].x&&puncte[i].y<puncte[m].y)
            m=i;
    }
    swap(puncte[1],puncte[m]);
    sort(puncte+2, puncte+n+1, comparator);
    int x=0;
    for (i=1;i<=n;i++)
    {
        while (x>1&&area(top[x-1],top[x],puncte[i])<0) x--;
        top[++x]=puncte[i];
    }
    fout<<x<<endl;
    for (int i=1;i<=x;i++)
        fout<<fixed<<top[i].x<<' '<<top[i].y<<'\n';
    return 0;
}