#include <fstream>
#include <algorithm>
#include <vector>
#include <iomanip>

#define x first
#define y second

using namespace std;

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

const int NMAX = 120000;

int N;
pair <long double, long double> v[NMAX + 5];

void Read()
{
    fin >> N;

    for(int i = 1; i <= N; i++)
        fin >> v[i].x >> v[i].y;
}

long double CrossProduct(pair <long double, long double> A, pair <long double, long double> B, pair <long double, long double> C)
{
    return (B.x - A.x) * (C.y - A.y) - (B.y - A.y) * (C.x - A.x);
}

inline bool cmp(pair <long double, long double> A, pair <long double, long double> B)
{
    return CrossProduct(v[1], A, B) > 0;
}

void ConvexHull()
{
    for(int i = 2; i <= N; i++)
        if(v[i] < v[1])
            swap(v[1], v[i]);

    sort(v + 2, v + N + 1, cmp);

    vector < pair <long double, long double> > convexHull;
    convexHull.push_back(v[1]);

    for(int i = 2; i <= N; i++)
        {
            while(convexHull.size() > 0 && CrossProduct(convexHull[(int)convexHull.size() - 2], convexHull[(int)convexHull.size() - 1], v[i]) < 0)
                convexHull.pop_back();

            convexHull.push_back(v[i]);
        }

    fout << convexHull.size() << '\n';
    for(auto it : convexHull)
        fout << fixed << setprecision(15) << it.x << ' ' << fixed << setprecision(15) << it.y << '\n';

}

int main()
{
    Read();

    ConvexHull();

    return 0;
}