#include <fstream>
#include <algorithm>
#include <iomanip>
using namespace std;
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");

int n, i, x, s;
pair <double, double> A[12010], sol[12010];
double det(const pair<double, double> &a, const pair<double, double> &b, const pair<double, double> &c) {
    return (b.first-a.first) * (c.second-a.second) - (c.first-a.first) * (b.second-a.second);
}
int cmp(const pair <double, double> &a, const pair< double, double> &b){
    return det(A[1], a, b) > 0;
}
int main()
{
    fin >> n;
    for(i = 1; i <= n; i ++)
        fin >> A[i].first >> A[i].second;
    int x = 1;
    for(i = 1; i <= n; i ++)
        if(A[x] > A[i])
            x = i;

    pair < double, double > aux = A[1];
    A[1] = A[x];
    A[x] = aux;

    sort(A + 2, A + n + 1, cmp);

    sol[1] = A[1];
    sol[2] = A[2];
    s = 2;
    for(i = 3; i <= n; i ++){
        while( s >= 2 && det(sol[s - 1], sol[s], A[i]) <= 0)
            s --;
        sol[++s] = A[i];
    }
    fout << s << '\n';
    for(i = 1; i <= s; i ++)
        fout << setprecision(9) << fixed << sol[i].first << " " << sol[i].second << '\n';
    return  0;
}