#include <iostream>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <math.h>
#include <iomanip>
#define dMAX 100
#define PI 3.141592

using namespace std;

int n;

struct Point{
    float x, y;
} arr[dMAX + 2], ymin;

Point myStack[dMAX + 2];
int idx, b;

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

float Angle(Point q) {
    float t = atan2(q.y - arr[1].y, q.x - arr[1].x);
    if (t < 0) return 2 * PI + t;
    return t;
}

bool Compare(Point p, Point q) {
    if (p.y == q.y) return p.x < q.x;
    return p.y < q.y;
}

bool CompareA(Point p, Point q) {
    return Angle(p) < Angle(q);
}

int Orientation(Point p, Point q, Point r) {
    int t = ((r.x - q.x) * (q.y - p.y) - (q.x - p.x) * (r.y - q.y));
    if (t < 0) return -1;
    if (t == 0) return 0;
    if (t > 0) return 1;
}

void Check(int id) {
    if (ymin.y > arr[id].y) {
        ymin.y = arr[id].y;
        ymin.x = arr[id].x;
        b = id;
    } else if (ymin.y == arr[id].y) {
        if (ymin.x > arr[id].x) {
            ymin.x = arr[id].x;
            b = id;
        }
    }
}

int main()
{
    int i, j;
    ymin.x = 2000000000;
    ymin.y = 2000000000;
    fin >> n;
    for (i = 1; i <= n; i++) {
        fin >> arr[i].x >> arr[i].y;
        Check(i);
    }
    if (n < 3) {
        fout << 0;
        return 0;
    }
    //sort(arr + 1, arr + 1 + n, Compare);
    swap(arr[1], ymin);
    sort(arr + 1, arr + 1 + n, CompareA);

    myStack[++idx] = arr[1];
    myStack[++idx] = arr[2];
    myStack[++idx] = arr[3];
    for (i = 4; i <= n; i++) {
        while (Orientation(myStack[idx - 1], myStack[idx], arr[i]) != -1 && idx >= 2) {
            idx--;
        }
        myStack[++idx] = arr[i];
    }
    if (idx < 3) {
        fout << 0;
        return 0;
    }
    fout << idx << '\n';
    for (i = 1; i <= idx; i++) {
        fout << setprecision(6) << fixed << myStack[i].x << ' ' << myStack[i].y << '\n';
    }

    return 0;
}