/*
    Those without power, seek us!
    Those with power, fear us!
    We are the Order of the Black Knights!
*/

#include<fstream>
#include<cstdio>
#include<map>
#include<set>
#define FIT(a,b) for(vector<int >::iterator a=b.begin();a!=b.end();a++)
#define FITP(a,b) for(vector<pair<int,int> >::iterator a=b.begin();a!=b.end();a++)
#define RIT(a,b) for(vector<int>::reverse_iterator a=b.end();a!=b.begin();++a)
#include<stack>
#define ROF(a,b,c) for(int a=b;a>=c;--a)
#include<vector>
#include<algorithm>
#define FOR(a,b,c) for(int a=b;a<=c;++a)
#define REP(a,b) for(register int a=0;a<b;++a)
#include<cstring>
#include<ctime>
#include<bitset>
#include<cmath>
#include<iomanip>
#include<set>
#define f cin
#define g cout
#include<queue>
#define debug cerr<<"OK";
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define ll long long
#define ull unsigned int
#define mod 1000000009LL
#define SQR 350
#define db double
#define inf 1<<30
#define div fdasfasd
#define hash dsafdsfds
#define od 100003
#define mod  1999999973LL
#define DIM 60010000
#define base 256
#define bas 255
#define N 120100
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");
/*
    int dx[]={0,0,0,1,-1};
    int dy[]={0,1,-1,0,0};
*/
pair<double,double> v[N];
int n,viz[N],s[N],t;
double det(db xa,db ya,db xb,db yb,db xc,db yc)
{
    return xa*yb+xb*yc+xc*ya-ya*xb-yb*xc-yc*xa;
}
int main ()
{
    f>>n;
    FOR(i,1,n)
    {
        f>>v[i].fi>>v[i].se;
    }
    sort(v+1,v+n+1);
    viz[2]=1;
    s[++t]=1;
    s[++t]=2;
    FOR(i,3,n)
    {
        while(t>=2&&det(v[s[t-1]].fi,v[s[t-1]].se,v[s[t]].fi,v[s[t]].se,v[i].fi,v[i].se)>=0)
        {
            viz[s[t]]=0;
            --t;
        }
        viz[i]=1;
        s[++t]=i;
    }
    ROF(i,n,1)
    {
        if(viz[i])
            continue;
        while(t>=2&&det(v[s[t-1]].fi,v[s[t-1]].se,v[s[t]].fi,v[s[t]].se,v[i].fi,v[i].se)>=0)
        {
            viz[s[t]]=0;
            --t;
        }
        viz[i]=1;
        s[++t]=i;
    }
    g<<t-1<<"\n";
    g<<fixed<<setprecision(7);
    FOR(i,1,t-1)
    g<<v[s[i]].fi<<" "<<v[s[i]].se<<"\n";
    return 0;
}