#include <cstdio>
	
 
	
#include <algorithm>
	
#include <fstream>
	
#include <iomanip>
	
 
	
using namespace std;
	
 
	
#define x first
	
#define y second
	
 
	
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 stack[MAX_N];
	
int head;
	
 
	
void read() {
	
    fin >> n;
	
    for (int i = 1; i <= n; ++i)
	
        fin >> v[i].x >> v[i].y;
	
}
	
 
	
inline double cross_product(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 cross_product(v[1], p1, p2) < 0;
	
}
	
 
	
void sort_points() {
	
    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 convex_hull() {
	
    sort_points();
	
 
	
    stack[1] = v[1];
	
    stack[2] = v[2];
	
    head = 2;
	
    for (int i = 3; i <= n; ++i) {
	
        while (head >= 2 && cross_product(stack[head - 1], stack[head], v[i]) > 0)
	
            --head;
	
        stack[++head] = v[i];
	
    }
	
}
	
 
	
void write() {
	
    fout << fixed;
	
    fout << head << "\n";
	
    for (int i = head; i >= 1; --i)
	
        fout << setprecision(9) << stack[i].x << " " << stack[i].y << "\n";
	
}
	
 
	
int main() {
	
    read();
	
    convex_hull();
	
    write();
	
}