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

#define x first
#define y second

using namespace std;

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

const int NMAX = 120000;

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

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

inline bool cmp(const pair<long double, long double> A, const pair<long double, long double> 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[1] > v[i]) swap(v[1], v[i]);

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

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

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

        hull.push_back(v[i]);
    }

    cout << (int)hull.size() << '\n';
    for(auto it : hull) {
        cout << fixed << setprecision(12) << it.x << ' ' << it.y << '\n';
    }

    return 0;
}