#include <bits/stdc++.h>
#define X first
#define Y second
#define punct pair<double,double>
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");
const int N = 120010;
const double eps = 0.000000001;
double dist(punct A,punct B)
{
    return (A.X-B.X)*(A.X-B.X)+(A.Y-B.Y)*(A.Y-B.Y);
}
double Det(punct A,punct B,punct C)
{
    return A.X*B.Y+B.X*C.Y+C.X*A.Y
        -( A.Y*B.X+B.Y*C.X+C.Y*A.X );
}
punct P[N],P0,P1;
double x,y;
int n;
bool crit(punct A,punct B)
{
    double aux=Det(P[0],A,B);
    if(aux>eps)return true;
    if(aux<-eps)return false;
    return dist(P[0],A)>dist(P[0],B);
}
vector<punct> sol;
int main()
{
    f>>n;
    for(int i=0;i<n;i++)
    {
        f>>x>>y;
        P[i]=make_pair(x,y);
        if(P[i]<P[0])swap(P[i],P[0]);
    }
    sort(P+1,P+n,crit);
    int top=2;
    for(int i=2;i<n;i++)
    {
        while(top>1&&Det(P[top-2],P[top-1],P[i])<0)
            top--;
        P[top++]=P[i];
    }
    g<<top<<'\n';
    for(int i=0;i<top;i++)
        g<<fixed<<setprecision(12)<<P[i].X<<' '<<P[i].Y<<'\n';
    return 0;
}