#include <bits/stdc++.h>
using namespace std;

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

struct point
{
    double x, y;
};

const int NMAX = 120005;
int n;
int idx[NMAX];
point arr[NMAX];

inline double det(point a, point b, point c)
{
    return (a.x*b.y + b.x*c.y + c.x*a.y - b.x*a.y - c.x*b.y - a.x*c.y);
}

inline bool Trig(const point &a, const point &b)
{
    return det(arr[1], a, b) > 0;
}

int main()
{
    fin >> n;
    
    for(int i = 1; i <= n; ++ i)
        fin >> arr[i].x >> arr[i].y;
        
    int minY = arr[1].y, minpos = 1;    
    
    for(int i = 1; i <= n; ++ i)
    {
        if(minY > arr[i].y)
        {
            minpos = i;
            minY = arr[i].y;
        }
    }
    swap(arr[1], arr[minpos]);
    sort(arr + 2, arr + n + 2, Trig);
 
    idx[1] = 1;
    idx[2] = 2;
    
    int k = 2;
    for(int i = 3; i <= n; ++i)
    {
        while(k > 1 && det(arr[idx[k-1]], arr[idx[k]], arr[i]) <= 0) 
            k--;
        idx[++k] = i;
    }
    
    fout << k << '\n';
    
    for(int i = 1; i <= k; ++ i)
        fout << fixed << setprecision(12) << arr[idx[i]].x << ' ' << arr[idx[i]].y << '\n';
}