#include <algorithm>
#include <fstream>
#include <iomanip>
 
using namespace std;

#define x second
#define y first

typedef pair<double, double> Point;
 
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
 
const int MAX_N = 120005;
 
int n;
Point v[MAX_N];
 
Point stk[MAX_N];
int top;
 
void Read() 
{
    fin >> n;
    for (int i = 1; i <= n; ++i)
        fin >> v[i].x >> v[i].y;
}
 
inline double CrossProduct(const Point& A, const Point& B, const Point& C) 
{
    return (B.x - A.x) * (C.y - A.y) - (B.y - A.y) * (C.x - A.x);
}
 
inline int Cmp(const Point& p1, const Point& p2) 
{
    return CrossProduct(v[1], p1, p2) > 0;
}
 
void SortPoints() 
{
    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);
}
 
void ConvexHull() 
{
    SortPoints();
 
    stk[1] = v[1];
    stk[2] = v[2];
    top = 2;
    for (int i = 3; i <= n; ++i) 
    {
        while (top >= 2 && CrossProduct(stk[top - 1], stk[top], v[i]) < 0)
            --top;
        stk[++top] = v[i];
    }
}
 
void Write() 
{
    fout << fixed;
    fout << top << '\n';
    for (int i = 1; i <= top; ++i)
        fout << setprecision(9) << stk[i].x << ' ' << stk[i].y << '\n';
}
 
int main() 
{
    Read();
    ConvexHull();
    Write();
}