/* 
 * File:   main.cpp
 * Author: virtualdemon
 *
 * Created on May 14, 2010, 11:02 AM
 */
#include <vector>
#include <cstdlib>
#include <fstream>
#include <iterator>
#include <algorithm>
#define oo 0x3f3f3f3f

/*
 * 
 */
using namespace std;
class point
{
    double x, y;
public:
    point( void ) : x(0.0), y(0.0) { }
    point( double _x, double _y ) : x(_x), y(_y) { }
    inline bool operator<( const point& ) const;
    inline bool cmp( const point& );
    inline bool cmp( const point&, const point& );
    friend inline istream& operator>>( istream&, point& );
    friend inline ostream& operator<<( ostream&, const point& );
} p0, p;
inline bool point::operator<( const point& z ) const
{
    double xx=( x-p0.x )*( z.y-p0.y ), yy=( y-p0.y )*( z.x-p0.x );
    if( xx == yy )
        return x < z.x || ( x == z.x && y < z.y );
    return xx < yy;
}
inline bool point::cmp( const point& z )
{
    return ( y > z.y  || (  y == z.y  && x > z.x   ) );
}
inline bool point::cmp( const point& p, const point& p2 )
{
    return ( x*p.y + p.x*p2.y + y*p2.x ) >= ( p.y*p2.x + p2.y*x + p.x*y );
}
inline istream& operator>>( istream& in, point& z )
{
    in>>z.x>>z.y;
    return in;
}
inline ostream& operator<<( ostream& out, const point& z )
{
    out<<fixed<<z.x<<' '<<z.y<<'\n';
    return out;
}

vector< point > v, ConvexHull;
int main( void )
{
    int N, i, j;
    ifstream in( "infasuratoare.in" );
    in>>N>>p0;
    for( i=1; i < N; ++i )
    {
        in>>p;
        if( p0.cmp(p) )
        {
            v.push_back(p0);
            p0=p;
            continue;
        }
        v.push_back(p);
    }
    sort( v.begin(), v.end() );
    ConvexHull.push_back(p0);
    ConvexHull.push_back(v[0]);
    ConvexHull.push_back(v[1]);
    for( i=2, N-=1; i < N; ++i )
    {
        p=v[i];
        for( j=ConvexHull.size(); j >= 2 && ConvexHull[j-2].cmp( ConvexHull[j-1], p ); --j )
            ConvexHull.pop_back();
        ConvexHull.push_back(p);
    }
    ofstream out( "infasuratoare.out" );
    out<<ConvexHull.size()<<'\n';
    copy( ConvexHull.rbegin(), ConvexHull.rend(), ostream_iterator<point>(out) );
    return EXIT_SUCCESS;
}