#include <bits/stdc++.h>
#define f first
#define s second
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");
typedef pair<double,double> point;

int n;
point a[120005];
double det(point a, point b, point c)
{
    return (a.f*b.s)+(a.s*c.f)+(b.f*c.s)-(b.s*c.f)-(a.s*b.f)-(c.s*a.f);
}
bool cmp(point l, point r)
{
    return det(a[1],l,r)>0;
}
int main()
{
    f>>n;
    int mn=1;

    for(int i=1; i<=n; i++)
    {
        f>>a[i].f>>a[i].s;
        if(a[i].f<a[mn].f)
            mn=i;

        else if(a[i].f==a[mn].f && a[i].s<a[mn].s )
            mn=i;
    }
    swap(a[1],a[mn]);
    sort(a+2,a+n+1,cmp);
    int l=2;
    a[n+1]=a[1];
    for(int i=3; i<=n+1; i++)
    {
        while(l>=2 && det(a[l-1],a[l],a[i])<0)
            l--;
        a[++l]=a[i];
    }
    g<<l-1<<'\n';
    for(int i=2; i<=l; i++)
        g<<fixed<<setprecision(6)<<a[i].f<<" "<<a[i].s<<'\n';
    return 0;
}