#include <iostream>
#include <fstream>
#include <vector>
#include <math.h>
#include <algorithm>
#include <iomanip>

using namespace std;

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

int n;
struct pp
{
    double x,y;
};

pp v[120001];
int m = 1;

bool ccw(pp a, pp b, pp c)
{
    if ( (b.x-a.x)*(c.y-a.y)  - (b.y - a.y)*(c.x - a.x) >= 0) return true;
    else return false;
}

bool comp(pp b, pp c)
{

    return ( (b.y-v[0].y)*(c.x - v[0].x)) <  (b.x - v[0].x)*(c.y-v[0].y );
}

int main()
{
    fin>>n;

    v[0].x=0;
    v[0].y=0;

    for (int i=0; i<n; i++)
        {
            pp x;
            fin>>x.x>>x.y;
            v[i+1]=x;
        }

    for (int i=1; i<=n; i++)
        if (v[i].y<=v[m].y)
        {
            if (v[i].y == v[m].y && v[i].x<v[m].x) m=i;
            else if (v[i].y != v[m].y) m=i;
        }

    swap(v[m],v[1]);
    v[0] = v[1];

    sort(v+2,v+n+1,comp);

    int a=1;

    for (int i=2; i<=n; i++)
    {
        while(!ccw(v[a-1],v[a],v[i]))
            if (a>1) a--;
            else if (i==n) break;
            else i++;
        a++;
        swap(v[i],v[a]);
    }

    fout<<a<<'\n';

    for (int i=1; i<=a; i++)
        fout<<setprecision(9)<<fixed<<v[i].x<<' '<<v[i].y<<'\n';


    return 0;
}