#include<stdio.h>
#include<vector>
#include<math.h>
#include <algorithm>
#define pb push_back

const int maxn = 120000;

using namespace std;

vector<int> VECT;
double X[maxn], Y[maxn];
int N, VER[maxn];

int main() {
  freopen("infasuratoare.in", "r", stdin);
  freopen("infasuratoare.out", "w", stdout);
  scanf("%d\n", &N);
  X[0] = 1000000000; Y[0] = 1000000000;
  for (int i = 1; i <= N; ++i)
    scanf("%lf %lf\n", &X[i], &Y[i]);
  int punct_initial = 0;
  int curent = 0;
  int move = 1;
  for(int i = 1; i <= N; ++i)
    if (X[i] < X[punct_initial]) punct_initial = i;
  curent = punct_initial;
  double last = 0;
  while(move || punct_initial != curent)
  {
    move = 0;
    VECT.pb(curent);
    double ma = 10000;
    int poznoua = curent;
    for(int i = 1; i <= N; ++i)
    {
      if (VER[i] || i == curent) continue;
      double unghi = atan2((X[i] - X[curent]), Y[i] - Y[curent]);
      if (unghi < 0) unghi += 2 * M_PI;
      unghi -= last;
      if (unghi < 0) unghi += 2 * M_PI;
      if (ma > unghi) {
        ma = unghi; poznoua = i;
      }
    }
    last = atan2(-(X[curent] - X[poznoua]), -(Y[curent] - Y[poznoua]));
    if (last < 0) last += 2 * M_PI;
    curent = poznoua;
    VER[curent] = 1;
  }
  reverse(VECT.begin(), VECT.end());
  printf("%d\n", VECT.size());
  for(unsigned int i = 0; i < VECT.size(); ++i)
    printf("%lf %lf\n", X[VECT[i]], Y[VECT[i]]);
  return 0;
}