#include<iostream>
#include<cstdio>
#include<algorithm>
#include<iomanip>
#include<fstream>
using namespace std;
typedef struct punct
{
    double x;
    double y;

}pct;
pct v[120000];
int st[120000];

double unghi(pct A, pct B, pct C)
{
    return (B.x-A.x)*(C.y-A.y)-(B.y-A.y)*(C.x-A.x);
}
int cmp(pct vi, pct vj)
{
    return (unghi(v[0], vi, vj)<0);
}
int main()
{
    FILE *fin, *fout;
    fin = fopen("infasuratoare.in", "r");
    ofstream g("infasuratoare.out");

    int n, i, prim, ultim;
    fscanf(fin, "%d", &n);
    for(i=0; i<n; i++)
        fscanf(fin, "%lf %lf", &v[i].x, &v[i].y);
    int min=0, auxx;
    for(i=1; i<n; i++)
        if(v[i].x<v[min].x)
            min=i;
        else
            if(v[i].x==v[min].x)
                if(v[i].y<v[min].y)
                    min=i;
    auxx=v[0].x;
    v[0].x=v[min].x;
    v[min].x=auxx;
    auxx=v[0].y;
    v[0].y=v[min].y;
    v[min].y=auxx;
    sort(v+1, v+n, cmp);
    st[0]=0;
    st[1]=1;
    prim=0; ultim=1;
    for(i = 2; i<n; i++)
    {
        while(unghi( v[st[ultim-1]], v[st[ultim]], v[i]) > 0 && ultim>=1)
            { ultim--; }
        ultim++;
        st[ultim]=i;
    }
    g<<ultim-prim+1<<"\n";
    for(i=ultim; i>=prim; i--)
    {
        g<<fixed<<setprecision(6)<<v[st[i]].x<<" "<<v[st[i]].y<<"\n";
    }

}