//Convex Hull - O(NlogN)
#include <fstream>
#include <cmath>
#include <cstdio>
#include <algorithm>
#define Precizie 1000000000000LL
#define eps 0.0000000000001
#define Nmax 120009
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");

int N,k;
struct point {double x,y;}P[Nmax],st[Nmax];

bool Equal(double x,double y)
{
    if(fabs(x-y)<eps) return 1;
    else return 0;
}

bool LessThan(double x, double y)
{
    if(1LL*Precizie*x<1LL*Precizie*y) return 1;
    else return 0;
}

double CrossProduct(point A,point B,point C)
{
    return (B.x-A.x)*(C.y-A.y)-(B.y-A.y)*(C.x-A.x);
}

bool cmp(point A, point B)
{
    return LessThan(0,CrossProduct(P[1],A,B));
}

void ConvexHull()
{
    sort(P+2,P+1+N,cmp);
    k=2;
    st[1]=P[1];
    st[2]=P[2];
    for(int i=3;i<=N;++i)
    {
        while(k>=2 && LessThan(CrossProduct(st[k-1],st[k],P[i]),0)) --k;
        st[++k]=P[i];
    }
}

int main()
{
    int j=1;
    f>>N;
    f>>P[1].x>>P[1].y;
    for(int i=2;i<=N;++i)
    {
        f>>P[i].x>>P[i].y;
        if(LessThan(P[i].y,P[j].y)) j=i;
            else if(Equal(P[i].y,P[j].y)&& LessThan(P[i].x,P[j].x)) j=i;
    }
    swap(P[1],P[j]);
    ConvexHull();
    g<<k<<'\n';
    g.precision(6);
    for(int i=1;i<=k;++i)
        g<<fixed<<st[i].x<<' '<<st[i].y<<'\n';
    f.close();g.close();
    return 0;
}