#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;}
const db EPS = (db)1e-12;
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 > > H;
    int sz = 0;
    cerr << fixed << setprecision(12);
    for (int i = 1;i <= n;++i) {
    	if (cmp(s[1],s[i],s[n]) <= EPS) {
    		while (sz >= 2 && cmp(H[sz - 2],H[sz - 1],s[i]) > EPS)
    			H.pop_back(),--sz;
    		H.pb(s[i]);
    		++sz;
    	} 
    }
    for (int i = n - 1;i >= 1;--i) {
    	if (cmp(s[1],s[i],s[n]) >= -EPS) {
    		while (sz >= 2 && cmp(s[i],H[sz - 1],H[sz - 2]) < EPS)
    			H.pop_back(),--sz;
    		H.pb(s[i]);
    		++sz;
    	}
    }
    cout << fixed << setprecision(6);
    cout << (sz - 1) << '\n';
    for (int i = 0;i + 1 < sz;++i)
    	cout << H[i].fi << ' ' << H[i].se << '\n';
    return 0;
}