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

#define NMax 120005
#define pb push_back
 
using namespace std;
 
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");

vector<int> VECT;
double X[NMax],Y[NMax];
int N,VER[NMax];
 
int main() {
    // Citire
    f>>N;
    X[0] = 1000000000;Y[0] = 1000000000;
    for(int i = 1;i <= N; ++i)
        f>>X[i]>>Y[i];

    // Aflarea punctului initial, cel mai de jos din stanga punct
    int punct_initial = 0;
    int cur = 0;
    int move = 1;
    for(int i = 1;i <= N; ++i)
        if (X[i] < X[punct_initial]) punct_initial = i;
    cur = punct_initial;
    double last = 0;
    
    while(move || punct_initial != cur) {
        move = 0;
        VECT.pb(cur);
        double ma = 10000;
        int poznoua = cur;
        for(int i = 1;i <= N; ++i) {
            if (VER[i] || i == cur) continue;
            double unghi = atan2((X[i] - X[cur]),Y[i] - Y[cur]);
            if (unghi < 0) unghi += 2* M_PI;
            unghi -= last;
            if (unghi < 0) unghi += 2 * M_PI;
            if (ma > unghi) {ma = unghi; poznoua = i;}
        }
        last = atan2(-(X[cur] - X[poznoua]),-(Y[cur] - Y[poznoua]));
        if (last < 0) last += 2 * M_PI;
        cur = poznoua;
        VER[cur] = 1;
    }

    reverse(VECT.begin(),VECT.end());
    g<<VECT.size()<<'\n';
    for(unsigned i = 0;i < VECT.size(); ++i)
        g<<fixed<<setprecision(12)<<X[VECT[i]]<<' '<<Y[VECT[i]]<<'\n';
    
    return 0;
}