#include <fstream>
#include <iostream>
#include <vector>
#include <stack>
#include <utility>//pair
#include <algorithm>
#include <assert.h>
#include <iomanip>
#define Inf (1<<31)-1

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

vector<pair<double,double> > v;
vector< pair<pair<double,double>, double> > nv;
pair<double,double> mini;
int n;

double abs(double x) {
    return (x<0? -x: x);
}


double tg(pair<double,double> a) {
    double x,y;
    x=(a.first - mini.first);
    y=(a.second - mini.second);
    if(x==0) {
        if (y == 0)
            return Inf;
        else
            return Inf-1;
    }
    return y/x;
}

int cmp(pair<double,double> a, pair<double,double> b) {
    double tg1, tg2;
    tg1 = tg(a);
    tg2 = tg(b);
    return tg1 > tg2;

}

void citire() {
    int i;
    double d1,d2;//

    scanf("%d", &n);
    mini.second=Inf;//
    mini.first=Inf;//
    for(i=1; i<=n; i++) {
        scanf("%lf %lf", &d1, &d2);
        if(d1<mini.first || (d1 == mini.first && d2 < mini.second))                          //luam cel mai din stanga punct si face tg adica y/x adica panta.
            mini=make_pair(d1,d2);
        v.push_back(make_pair(d1,d2));
    }
}

int left_turn(pair<double, double> p1, pair<double, double> p2, pair<double, double> p3) {
    return (p1.first*p2.second)-(p2.second*p3.first)+(p2.first*p3.second)-(p2.first*p1.second)+(p1.second*p3.first)-(p3.second*p1.first);

}

int main() {
    freopen("infasuratoare.in","rt",stdin);
    freopen("infasuratoare.out","wt",stdout);
    citire();
    sort(v.begin(),v.end(),cmp);

    vector<int> S;
    S.push_back(0);
    for(int i=1; i<n; i++) {
        while(S.size() >= 2 && left_turn(v[ S[S.size()-2] ], v[S.back()], v[i]) > 0)
            S.pop_back();               //daca noul nod e mai la stanga
        S.push_back(i);                             //punctul nou
    }

    int sz = S.size();
    cout<<sz<<'\n';
    for(int i=0; i<S.size(); ++i) {
        //printf ("%.2lf %.2lf\n", v[emij].first, v[emij].second);
        cout<<fixed<<setprecision(6)<<v[S[i]].first<<' '<<v[S[i]].second<<'\n';
    }



    return 0;
}