#include<fstream>
#include<algorithm>
#include<iomanip>

using namespace std;
#define Nmax 120005

ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
struct punct{
    double x,y;
};

punct a[Nmax];
int n,k ;
int s[Nmax];

double panta(punct p, punct q,punct fix){
    double rez;
    rez=(p.y-fix.y)*(q.x-fix.x)-(q.y-fix.y)*(p.x-fix.x);
    return rez;
}
bool cmp(punct  p,punct q){

    return panta(p,q,a[1])<0;
}
int main(){
    int i,pmin;
    double minx=1e9,miny=1e9;
    fin>>n;
    for(i=1;i<=n;++i){
        fin>>a[i].x>>a[i].y;
        if(a[i].x<minx){
            minx=a[i].x;
            miny=a[i].y;
            pmin=i;
        }
        else
        if(a[i].x==minx && a[i].y<miny){
            miny=a[i].y;
            pmin=i;
        }
    }

    swap(a[1],a[pmin]);
    sort(a+2,a+n+1,cmp);

    s[1]=1;s[2]=2;k=2;

    for(i=3;i<=n;i++){
            while(k>2 && panta(a[s[k-1]],a[s[k]],a[i])>0)
                k--;
            s[++k]=i;
    }
    fout<<k<<"\n";
    for(i=1;i<=k;i++){
        fout<<fixed<<setprecision(6)<<a[s[i]].x<<" "<<a[s[i]].y<<"\n";
    }
    return 0;
}