#include <bits/stdc++.h>
#define MAX 120000
#define INF 2e9

using namespace std;

struct Point
{
    double x;
    double y;
}v[MAX];

double crossProduct(Point a, Point b, Point c)
{
    double x1 = b.x - a.x;
    double y1 = b.y - a.y;
    double x2 = c.x - a.x;
    double y2 = c.y - a.y;

    return y2 * x1 - y1 * x2;
}

bool greaterDistance(Point a, Point b, Point c)
{
    double x1 = b.x - a.x;
    double y1 = b.y - a.y;
    double x2 = c.x - a.x;
    double y2 = c.y - a.y;

    return (x1 * x1 + y1 * y1) < (x2 * x2 + y2 * y2);
}

int main()
{
    int n;

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

    ios::sync_with_stdio(false);
    fin.tie(0);
    fout.tie(0);
    srand(time(NULL));

    fin >> n;

    int minPointX = 1;
    for(int i = 1; i <= n; i++)
    {
        fin >> v[i].x >> v[i].y;

        if(v[i].x < v[minPointX].x)
            minPointX = i;
    }

    vector<int>convexHull;

    convexHull.push_back(minPointX);
    int currentPoint = minPointX;

    do
    {
        int nextPoint = currentPoint;

        for(int i = 1; i <= n; i++)
        {
            if(i == currentPoint)continue;

            if(crossProduct(v[currentPoint], v[nextPoint], v[i]) < 0)
                nextPoint = i;
            else if(crossProduct(v[currentPoint], v[nextPoint], v[i]) == 0)
                if(greaterDistance(v[currentPoint], v[nextPoint], v[i]))
                    nextPoint = i;
        }

        convexHull.push_back(nextPoint);
        currentPoint = nextPoint;
    }while(currentPoint != convexHull[0]);

    convexHull.pop_back();

    fout << convexHull.size() << '\n';
    fout << fixed;
    fout.precision(12);

    for(auto point : convexHull)
        fout << v[point].x << " " << v[point].y << '\n';

    fin.close();
    fout.close();

    return 0;
}