#include <bits/stdc++.h>

using namespace std;

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

const int Nmax = 130005;

int n, k;

struct Punct
{
    double x, y;
};
Punct v[Nmax], s[Nmax];

double Det(const Punct &a, const Punct &b, const Punct &c)
{
    return (b.x - a.x) *(c.y - a.y) - (c.x - a.x) * (b.y - a.y);
}

inline bool CMP(const Punct &a,const Punct &b)
{
    return Det(v[1], a, b) > 0;
}

void Read()
{
    int i;
    fin >> n;
    for (i = 1; i <= n; i++)
        fin >> v[i].x >> v[i].y;
    fin.close();
}
void Do()
{
    int i, j, p;
    p = 1;
    for (i = 2; i <= n; i++)
        if (v[i].y < v[p].y || (v[i].y == v[p].y && v[i].x < v[i].x)) p = i;

    swap(v[1], v[p]);

    sort(v + 2, v + n + 1, CMP);
    s[++k] = v[1];
    s[++k] = v[2];
    for (i = 3; i <= n; i++)
        {
        while (k >= 2 && Det(s[k-1], s[k], v[i]) < 0) k--;

        s[++k]=v[i];
    }
}

void Write()
{
    int i;
    fout << k << "\n";
    for (i = 1; i <= k; i++)
        fout << setprecision(9) << fixed << s[i].x << " " << s[i].y << "\n";
    fout.close();
}

int main()
{
    Read();
    Do();
    Write();
    return 0;
}