#include <stdio.h>
# include <algorithm>
# include <math.h>
# include <vector>
using namespace std;
int n,i,in,c,poz;
double u,z,unghi,x[120000],y[120000];
bool use[120000],ok;
vector <int> v;
int main()
{
    freopen("infasuratoare.in","r",stdin);
    freopen("infasuratoare.out","w",stdout);
    scanf("%d\n",&n);
    for (i=1; i<=n; i++)
    {
        scanf("%lf %lf",&x[i],&y[i]);
    }
    in=1;
    for (i=2; i<=n; i++)
        if (x[i]<x[in]) in=i;
    c=in;
    ok=true;
    u=0;
    while (ok==true || in!=c)
    {
        ok=false;
        v.push_back(c);
        z=100000;
        for (i=1; i<=n; i++)
        {
            if (use[i] || i==c) continue;
            unghi=atan2((x[i]-x[c]),(y[i]-y[c]));
            if (unghi<0) unghi+=2*M_PI;
            unghi-=u;
            if (unghi<0) unghi+=2*M_PI;
            if (z>unghi)
            {
                z=unghi;
                poz=i;
            }
        }
        u=atan2(-(x[c]-x[poz]),-(y[c]-y[poz]));
        if (u<0) u+=2*M_PI;
        c=poz;
        use[c]=true;
    }
    reverse(v.begin(),v.end());
    printf("%d\n",v.size());
    for (i=0;i<v.size(); i++)
         printf("%lf %lf\n",x[v[i]],y[v[i]]);
    return 0;
}