#include <bits/stdc++.h>
#define NMAX 120005
using namespace std;
ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");
typedef long double ld;
struct punct{ld x,y;}P[NMAX];
ld minx=1000000000,miny=1000000000,R0;
punct S[NMAX];
int N;
int varf;
bool comp(punct a, punct b)
{
    return ((a.y-miny)*(b.x-minx) < (b.y-miny)*(a.x-minx) || (a.y-miny)*(b.x-minx) == (b.y-miny)*(a.x-minx) && (a.x-minx)*(a.x-minx) + (a.y-miny)*(a.y-miny) > (b.x-minx)*(b.x-minx) + (b.y-miny)*(b.y-miny));
}
bool stare(punct A, punct B, punct C);
ld det(punct A, punct B, punct C);
int main()
{
    int i;
    ld val;
    punct P1,P2,P3;
    fin >> N;
    for(i=1;i<=N;++i)
    {
        fin>>P[i].x>>P[i].y;
        if(P[i].y < miny || P[i].y == miny && P[i].x < minx) miny = P[i].y, minx=P[i].x;

    }
    sort(P+1,P+N+1,comp);
    S[++varf]={minx,miny};
    for(i=1;i<N;++i)
    {
        P1=S[varf];
        P2=P[i];
        P3=P[i+1];
        val = stare(P1,P2,P3);
        if(val == 1) S[++varf]=P2;
        else {
            varf -- ;
            P[i] = P1;
            i--;
        }
    }
    fout<<varf<<"\n";
    for(int i=1;i<=varf;++i)
        fout<<fixed << setprecision(12) << S[i].x<<" "<<S[i].y<<"\n";
    return 0;
}
ld det(punct A, punct B, punct C)
{
    return (A.x*B.y + B.x*C.y + C.x*A.y - B.y*C.x - C.y*A.x - A.y*B.x);
}
bool stare(punct A, punct B, punct C)
{
    if(det(A,B,C) > 0) return 1;
    else return 0;
}