#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define ft first
#define sc second
#define ll long long
ifstream fin("infasuratoare.in"); ofstream fout("infasuratoare.out");
int n;
vector<pair<double, double> > p;
double cross_product( pair<double, double> &p1, pair<double, double> &p2, pair<double, double> &p3 ){
return (p2.ft-p1.ft)*(p3.sc-p2.sc)-(p3.ft-p2.ft)*(p2.sc-p1.sc);
}
bool e(pair<double, double> a, pair<double, double> b){
return a.ft<b.ft || ( (a.ft==b.ft) && (a.sc<b.sc) );
}
int main(){
fin>>n;
p.resize(n);
int p0=0;
for(int i=0; i<n; i++){
fin>>p[i].ft>>p[i].sc;
if(p[i].sc<p[p0].sc){
p0=i;
}
else{
if(p[i].sc==p[p0].sc){
if(p[i].ft<p[p0].ft){
p0=i;
}
}
}
}
sort(p.begin(), p.end(), e);
for(int i=2; i<p.size(); i++){
while( i>=2 && cross_product( p[i-2], p[i-1], p[i] )<=0 ){
p.erase(p.begin()+i-2+1, p.begin()+i-2+2 ); i--;
}
}
fout<<p.size()<<"\n";
for(int i=0; i<p.size(); i++){
fout<<fixed<<setprecision(9)<<p[i].ft<<" "<<p[i].sc<<"\n";
}
return 0;
}