#include <bits/stdc++.h>

#define EPS 1e-12
#define NMAX 121105
using namespace std;

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

int poz = 2;

struct punct
{
    long double x, y;
} v[NMAX], st[NMAX];

long double det(punct a, punct b, punct c){
    return ((a.x * b.y + a.y * c.x + b.x * c.y) - (b.y * c.x + a.y * b.x + a.x * c.y));
}

inline bool cmp1(punct a, punct b){
    return a.y < b.y;
}

inline bool cmp2(punct a, punct b){
    return (det(v[1], a, b) > 0.0);
}

inline bool test(punct a){
    while(poz > 1 && det(st[poz - 1], st[poz], a) <= 0.0)
        --poz;
    st[++poz] = a;
}

int main()
{
    int n;
    fin >> n;

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

    sort(v + 1, v + n + 1, cmp1);
    sort(v + 2, v + n + 1, cmp2);
    st[1] = v[1];
    st[2] = v[2];
    for(int i = 3; i <= n; ++i)
        test(v[i]);
    test(v[1]);
    --poz;

    fout << poz << '\n';
    for(int i = 1; i <= poz; ++i)
        fout << fixed << setprecision(6) << st[i].x << ' ' << st[i].y << '\n';
    return 0;
}