#include <bits/stdc++.h>

using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");

struct point{
	double x, y;
}v[120100], st[120100];

int n, vf;

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

int comp1(point A,point B)
{
    if(A.x==B.x) return (A.y<B.y);
        else return (A.x<B.x);
}

int comp2(point B,point C)
{
    return (det(v[1],B,C)<0);
}
int main()
{
    int i;
    f>>n;
      for(i=1;i<=n;i++)
    f>>v[i].x>>v[i].y;

    sort(v+1,v+n+1,comp1);
	st[1]=v[1];

    sort(v+2,v+n+1,comp2);
    st[2]=v[2];

    vf = 2;

    for(i=3;i<=n;i++)
    {
      while(vf>2 && det(st[vf-1],st[vf],v[i])>0) vf--;
      st[++vf]=v[i];
    }

    g<<vf<<'\n';
    for(i=vf;i>=1;i--)
        g<<fixed<<setprecision(6)<<st[i].x<<" "<<st[i].y<<" "<<'\n';

   return 0;
}