#include <bits/stdc++.h>
using namespace std;

ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");

const int dim=200000;

struct pt{
    long double x,y;
    int ind;
    bool operator <(const pt &other) const
    {
        if(x==other.x){
            return y<other.y;
        }
        return x<other.x;
    }
}v[dim];

int ap[dim],stiva[dim],vf;
vector<pt>e;

bool cross(pt a,pt b,pt c){
    return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x)<=0;
}

void solve(){
    vf=0;
    for(auto it:e){
        long double y=it.y;
        int ind=it.ind;
        while(vf>=2 && cross(v[stiva[vf-1]],v[stiva[vf]],v[ind])){
            ap[stiva[vf]]--;
            vf--;
        }
        stiva[++vf]=ind;
        ap[ind]++;
    }
    vf=0;
    reverse(e.begin(),e.end());
    for(auto it:e){
        long double y=it.y;
        int ind=it.ind;

        while(vf>=2 && cross(v[stiva[vf-1]],v[stiva[vf]],v[ind])){
            ap[stiva[vf]]--;
            vf--;
        }
        stiva[++vf]=ind;
        ap[ind]++;
    }
}

signed main(){
    int n;
        fin>>n;
    for(int i=1;i<=n;i++){
        fin>>v[i].x>>v[i].y;
        e.push_back({v[i].x,v[i].y,i});
    }
    sort(e.begin(),e.end());
    solve();
    int nr=0;
    for(int i=1;i<=n;i++){
        if(ap[i]){
            nr++;
        }
    }
            fout<<nr<<'\n';
    for(int i=1;i<=n;i++){
        if(ap[i]){
            fout<<fixed<<setprecision(12)<<v[i].x<<' '<<v[i].y<<'\n';
        }
    }
}