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

using namespace std;

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

const int NMAX = 120000;

struct Point {
    long double x, y;

    bool operator < (const Point other) const {
        if(x == other.x)
            return y < other.y;

        return x < other.x;
    }
};

int N;
Point v[NMAX + 5];

int vf;
Point st[NMAX + 5];

bool ccw(Point A, Point B, Point C)
{
    return (B.y - A.y) * (C.x - A.x) < (C.y - A.y) * (B.x - A.x);
}

inline bool cmp(const Point A, const Point B)
{
    return ccw(v[1], A, B);
}

int main()
{
    cin >> N;

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

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

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

    for(int i = 1; i <= N; i++) {
        while(vf > 1 && !ccw(st[vf - 1], st[vf], v[i]))
            vf--;

        st[++vf] = v[i];
    }

    cout << vf << '\n';
    for(int i = 1; i <= vf; i++)
        cout << fixed << setprecision(12) << st[i].x << ' ' << st[i].y << '\n';

    return 0;
}