#include <bits/stdc++.h>
#define Nmax 120005
#define eps 0.000000000001

using namespace std;

struct Point
{
    double x,y;
    bool operator <(const Point &A) const
    {
        if(fabs(y-A.y)<=eps) return A.x-x>eps;
        return A.y-y>eps;
    }
} a[Nmax];
int st[Nmax],top,used[Nmax],n;

inline bool Good(Point &A, Point &B, Point &C)
{
    double alfa = B.y-A.y;
    double beta = A.x-B.x;
    double gama = B.x*A.y - A.x*B.y;

    return (alfa*C.x + beta*C.y + gama <= eps);
}

inline void Convex_hull()
{
    int i,sign=1;
    st[++top]=1; st[++top]=2;
    used[2]=1;
    for(i=3;i;i+=sign)
    {
        if(used[i]) continue;
        if(i==n) sign=-1;
        while(top>1 && !Good(a[st[top-1]],a[st[top]],a[i])) used[st[top--]]=0;
        st[++top]=i; used[i]=1;
    }
}

int main()
{
    int i;
    ifstream cin("infasuratoare.in");
    ofstream cout("infasuratoare.out");
    cin>>n;
    for(i=1;i<=n;++i) cin>>a[i].x>>a[i].y;
    sort(a+1,a+n+1);
    Convex_hull();
    cout<<top-1<<"\n";
    cout<<setprecision(10)<<fixed;
    for(i=1;i<top;++i) cout<<a[st[i]].x<<" "<<a[st[i]].y<<"\n";
    return 0;
}