#include <bits/stdc++.h>

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 st[MAX_N];
int head;

double det(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);
}

bool cmp(const Point& p1, const Point& p2) {
  return det(v[1], p1, p2) < 0;
}

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

  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);

   st[1] = v[1];
   st[2] = v[2];
   head = 2;
   for (int i = 3; i <= n; i++) {
     while (head >= 2 && det(st[head - 1], st[head], v[i]) > 0) {
       --head;
     }

     st[++head] = v[i];
   }

   fout << fixed;
   fout << head << "\n";
   for (int i = head; i >= 1; i--) {
     fout << setprecision(9) << st[i].x << " " << st[i].y << "\n";
   }

  return 0;
}