#include cstdio
 
#include algorithm
#include fstream
#include iomanip
 
using namespace std;
 
#define x first
#define y second
 
typedef pairdouble, 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();
}