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

using namespace std;
const int NMAX = 120002;
using ld = long double;

ifstream cin("infasuratoare.in");
ofstream cout("infasuratoare.out");

struct puncte {
    ld x, y;
}v[NMAX];

ld panta(puncte p0, puncte a, puncte b) { ///comp pantele (0, a), (0, b)
    ld nr1 = (a.y - p0.y) * (b.x - p0.x);
    ld nr2 = (a.x - p0.x) * (b.y - p0.y);
    return nr1 < nr2;
}
bool cmp(puncte a, puncte b) {
    return panta(v[1], a, b);
}
ld determ(puncte a, puncte b, puncte c) { ///aria triun
    return a.x * b.y + b.x * c.y + c.x * a.y -
           b.y * c.x - c.y * a.x - a.y * b.x;
}


vector <puncte> s;
int main()
{
    int n, pos = -1;
    puncte p0 = {1000000001, 1000000001}; ///pct cel mai din st
    cin >> n;
    for(int i = 1; i <= n; i++) {
        cin >> v[i].x >> v[i].y;
        if((v[i].x < p0.x) || (v[i].x == p0.x && v[i].y < p0.y)) {
            p0 = v[i];
            pos = i;
        }
    }
    if(pos > 1)
        swap(v[1], v[pos]);
    cout << v[1].x << " " << v[1].y << '\n';
    sort(v + 2, v + n + 1, cmp);
    for(int i = 2; i <= n; i++)
        cout << v[i].x << " " << v[i].y << '\n';
    cout << '\n';
    s.push_back(v[1]);
    s.push_back(v[2]);
    for(int i = 3; i <= n; i++) {
        while(s.size() >= 2 && determ(s[s.size() - 2], s[s.size() - 1], v[i]) < 0) {
            //cout << "DECI " << i << '\n';
            //cout << s[s.size() - 2].x << " " << s[s.size() - 2].y << '\n';
            //cout << s[s.size() - 1].x << " " << s[s.size() - 1].y << '\n';
            //cout << v[i].x << " " << v[i].y << '\n';
            //cout << determ(s[s.size() - 2], s[s.size() - 1], v[i]) << '\n';
            s.pop_back();
        }
        s.push_back(v[i]);
        //cout << "yoo " << i << "  " << s.size() << '\n';
    }
    cout << s.size() << '\n';
    for(auto var : s)
        cout << setprecision(12) << fixed << var.x << " " << var.y << '\n';
    return 0;
}