#include <iostream>
#include <fstream>
#include <map>
#include <string.h>
#include <string>
#include <vector>
#include <set>
#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;
};

vector<pp> v;
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 ( atan2(b.y-v[0].y,b.x - v[0].x)<atan2(c.y-v[0].y,c.x - v[0].x) );
}

int main()
{
    fin>>n;

    {
    pp t;
    t.x=0;
    t.y = 0;
    v.push_back(t);
    }

    for (int i=0; i<n; i++)
        {
            pp x;
            fin>>x.x>>x.y;
            v.push_back(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.begin()+2,v.end(),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;
}