#include <bits/stdc++.h>
#define x first
#define y second

using namespace std;

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

typedef pair<double, double> point;
const int nmax = 120005;
int n;
point v[nmax];
point st[nmax];
int top;

inline void read()
{
    fin >> n;
    for (int i = 1; i <= n;  i++)
        fin >> v[i].x >> v[i].y;
}

inline double cross(point &a, point &b, point &c)
{
    //unghiul polar de la ab la c
    return ((b.y - a.y)*(c.x - b.x) - (c.y - b.y)*(b.x - a.x));
}

bool cmp(point a, point b)
{
    return (cross(v[1], a, b) < 0);
}

inline void sortt()
{
    int pos = 1;
    for (int i = 2; i <= n; i++)
        if (v[i] < v[pos])
            pos = i;
    swap(v[1], v[pos]);
    sort(v + 2, v + n + 1, cmp);
}

inline void convex_hull()
{
    st[++top] = v[1];
    st[++top] = v[2];
    for (int i = 3; i <= n; i++)
    {
        while (top >= 2 && cross(st[top-1], st[top], v[i]) > 0)
            top--;
        st[++top] = v[i];
    }
    fout << fixed;
    fout << top << "\n";
    for (int i = 1; i <= top; i++)
         fout << setprecision(12) << st[i].x << " " << st[i].y << "\n";
}

int main()
{
    read();
    sortt();
    convex_hull();
    return 0;
}