#include <bits/stdc++.h>

using namespace std;

#define x first
#define y second

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

int n, poz = 1;
pair <double, double> puncte[120005], stiva[120005];

double cross_product(pair <double, double> a, pair <double, double> b, pair <double, double> c)
{
    return ((b.x - a.x) * (c.y - a.y) - (c.x - a.x) * (b.y - a.y));
}

bool cmp(pair <double, double> a, pair <double, double> b)
{
    return cross_product(puncte[1], a, b) < 0;
}

int main()
{
    fin >> n;
    for (int i = 1; i <= n; ++i)
    {
        fin >> puncte[i].x >> puncte[i].y;
        if (puncte[i] < puncte[poz]) poz = i;
    }
    swap(puncte[1], puncte[poz]);
    sort(puncte + 2, puncte + n + 1, &cmp);
    for (int i = 1; i <= n; ++i)
    {
        cout << puncte[i].x << ' ' << puncte[i].y << '\n';
    }
    stiva[1] = puncte[1];
    stiva[2] = puncte[2];
    int cap = 2;
    for (int i = 3; i <= n; ++i)
    {
        if (cap >= 2 && cross_product(stiva[cap - 1], stiva[cap], puncte[i]) > 0)
            cap--;
        stiva[++cap] = puncte[i];
    }
    fout << cap << '\n';
    for (int i = 1; i <= cap; ++i)
    {
        fout << fixed << setprecision(9) << stiva[i].x << ' ' << stiva[i].y << '\n';
    }
    return 0;
}