#include<fstream>
#include<iostream>
#include<vector>
#include<algorithm>
#include<iomanip>
#define DN 120005
#define x first
#define y second
using namespace std;
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
int n,st[DN],k,v[DN],pmin;
double pminx,pminy;
pair<double,double>x[DN];
typedef pair<double,double> pii;
double det(int a,int b,int c)
{
    double ce=x[a].x*x[b].y+x[b].x*x[c].y+x[c].x*x[a].y;
    double d=x[b].y*x[c].x+x[c].y*x[a].x+x[a].y*x[b].x;
    return ce-d;
}
int sem(double x)
{
    if(x>0)
        return 1;
    if(x==0)
        return 0;
    return -1;
}
int cmp(pii A,pii B)
{
    double a,b;
    if(A.x==0)
        a=sem(A.y)*(1<<28);
    else
        a=A.y/A.x;
    if(B.x==0)
        b=sem(B.y)*(1<<28);
    else
        b=B.y/B.x;
    return a<b;
}
int main()
{
    fin>>n;
    for(int i=1;i<=n;i++)
        fin>>x[i].x>>x[i].y;
    sort(x+1,x+n+1);
    sort(x+2,x+n+1,cmp);
    for(int i=1;i<=n;i++)
    {
        while(k>1&&det(st[k-1],st[k],i)<0)
        {
            v[st[k]]=0;
            k--;
        }
        k++;
        st[k]=i;
        v[i]=1;
    }
   /* for(int i=n;i>=1;i--)
        if(!v[i])
    {
        while(k>1&&det(st[k-1],st[k],i)<0)
        {
            v[st[k]]=0;
            k--;
        }
        k++;
        st[k]=i;
        v[i]=1;
    }*/
    fout<<k<<'\n';
    for(int i=1;i<=k;i++)
        fout<<fixed<<setprecision(12)<<x[st[i]].x<<' '<<x[st[i]].y<<'\n';
}