#include "bits/stdc++.h"
using namespace std;
#define fi first
#define se second
#define ll long long
#define dbg(v) cerr<<#v<<" = "<<v<<'\n'
#define vi vector<int>
#define vl vector <ll>
#define pii pair<int,int>
#define vii vector < pii >
#define mp make_pair
#define db long double
#define pb push_back
#define all(s) s.begin(),s.end()
template < class P , class Q > ostream& operator<<(ostream& stream, pair < P , Q > v){ stream << "(" << v.fi << ',' << v.se << ")"; return stream;}
template < class T > ostream& operator<<(ostream& stream, const vector<T> v){ stream << "[ "; for (int i=0; i<(int)v.size(); i++) stream << v[i] << " "; stream << "]"; return stream;}
template < class T > T smin(T &a,T b) {if (a > b) a = b;return a;}
template < class T > T smax(T &a,T b) {if (a < b) a = b;return a;}
auto cmp(auto a,auto b,auto c) {
	return a.fi * (b.se - c.se) - a.se * (b.fi - c.fi) + b.fi * c.se - b.se * c.fi;
}
const int N = 2e5 + 5;
pair < db , db > s[N];
int main(void) {
    ifstream cin("infasuratoare.in");
    ofstream cout("infasuratoare.out");
    int n;
    cin>>n;
    for (int i = 1;i <= n;++i)
    	cin>>s[i].fi>>s[i].se;
    sort(s + 1,s + 1 + n);
    vector < pair < db , db > > A,B,ans;
    int sz1 = 0,sz2 = 0;
    for (int i = 1;i <= n;++i) {
    	if (cmp(s[1],s[i],s[n]) <= 0) {
    		while (sz1 >= 2 && cmp(A[sz1 - 2],A[sz1 - 1],s[i]) > 0)
    			A.pop_back(),--sz1;
    		A.pb(s[i]);
    		++sz1;
    	} 
    }
    for (int i = n;i >= 1;--i) {
    	if (cmp(s[1],s[i],s[n]) >= 0) {
    		while (sz2 >= 2 && cmp(s[i],B[sz2 - 1],B[sz2 - 2]) < 0)
    			B.pop_back(),--sz2;
    		B.pb(s[i]);
    		++sz2;
    	}
    }
    cout << fixed << setprecision(6);
    cout << (sz1 + sz2 - 2) << '\n';
    for (int i = 0;i < sz1;++i)
    	cout << A[i].fi << ' ' << A[i].se << '\n';
    for (int i = sz2 - 2;i > 0;--i)
    	cout << B[i].fi << ' ' << B[i].se << '\n';
    return 0;
}