#include <bits/stdc++.h>

/**

                                          `-.`'.-'
                                       `-.        .-'.
                                    `-.    -./\.-    .-'
                                        -.  /_|\  .-
                                    `-.   `/____\'   .-'.
                                 `-.    -./.-""-.\.-      '
                                    `-.  /< (()) >\  .-'
                                  -   .`/__`-..-'__\'   .-
                                ,...`-./___|____|___\.-'.,.
                                   ,-'   ,` . . ',   `-,
                                ,-'   ________________  `-,
                                   ,'/____|_____|_____\
                                  / /__|_____|_____|___\
                                 / /|_____|_____|_____|_\
                                ' /____|_____|_____|_____\
                              .' /__|_____|_____|_____|___\
                             ,' /|_____|_____|_____|_____|_\
,,---''--...___...--'''--.. /../____|_____|_____|_____|_____\ ..--```--...___...--``---,,
                           '../__|_____|_____|_____|_____|___\
      \    )              '.:/|_____|_____|_____|_____|_____|_\               (    /
      )\  / )           ,':./____|_____|_____|_____|_____|_____\             ( \  /(
     / / ( (           /:../__|_____|_____|_____|_____|_____|___\             ) ) \ \
    | |   \ \         /.../|_____|_____|_____|_____|_____|_____|_\           / /   | |
 .-.\ \    \ \       '..:/____|_____|_____|_____|_____|_____|_____\         / /    / /.-.
(=  )\ `._.' |       \:./ _  _ ___  ____  ____ _    _ _ _ _ _  _ __\        | `._.' /(  =)
 \ (_)       )        \/                                            \       (       (_) /
  \    `----'          """"""""""""""""""""""""""""""""""""""""""""""        `----'    /
   \   ____\__                                                              __/____   /
    \ (=\     \                                                            /     /-) /
     \_)_\     \                                                          /     /_(_/
          \     \                                                        /     /
           )     )  _                                                _  (     (
          (     (,-' `-..__                                    __..-' `-,)     )
           \_.-''          ``-..____                  ____..-''          ``-._/
            `-._                    ``--...____...--''                    _.-'
                `-.._                                                _..-'
                     `-..__               AKRIEL               __..-'
                           ``-..____                  ____..-''
                                    ``--...____...--''

*/

using namespace std;

#define coordonates pair <double, double>
#define x first
#define y second

ifstream fin("infasuratoare.in");
ofstream fout("infasuratoare.out");

const int N {120005};

/*
struct coordonates{
    double x;
    double y;

    coordonates (void){
    };

    coordonates (double x, double y){
        this->x = x;
        this->y = y;
    }

    bool lowerThan(coordonates B){
        if ( y < B.y )
            return true;
        if ( x < B.x and y == B.y )
            return true;
        return false;
    }

};
*/

coordonates points[N], leftBottom, Stack[N] ;

int totalPoints, positionLeftBottom, top;

double aria(coordonates A, coordonates B, coordonates C){
    return A.x*B.y + B.x*C.y + C.x*A.y - C.x*B.y - B.x*A.y - A.x*C.y;
}

double epsilon = 0.00000001;

bool compare(coordonates A, coordonates B, coordonates C = points[1]){
    double delta = aria(A, B, C);
    if ( delta > epsilon )
        return true;
    if ( delta < -epsilon )
        return false;
    return false;
}

bool trigger(coordonates A, coordonates B){
    return compare(A, B);
}

inline void readVariables(void){
    double x, y;
    fin >> totalPoints;
    fin >> x >> y;
    points[1] = {x, y};
    leftBottom = points[1];
    positionLeftBottom = 1;
    for ( int index = 2; index <= totalPoints; index++ ){
        fin >> x >> y;
        points[index] = {x, y};
        if ( points[index] < leftBottom ){
            positionLeftBottom = index;
            leftBottom = points[index];
        }
    }
    swap(points[positionLeftBottom], points[1]);
}

inline void convexHull(void){
    Stack[1] = points[1];
    Stack[2] = points[2];
    top = 2;
    for ( int index = 3; index <= totalPoints; index++ ){
        for ( ; !compare(Stack[top-1], Stack[top], points[index]); )
            top--;
        Stack[++top] = points[index];
    }

}

inline void displayPoints(void){
    for ( int index = 1; index <= totalPoints; index++ )
        cout << points[index].x << " " << points[index].y << "\n";
    cout << "\n";
}

inline void solveProblem(void){
    sort (points+1, points+totalPoints+1, trigger);
    convexHull();
    fout << top << "\n";
    for ( int index = 1; index <= top; index++ )
        fout << fixed << setprecision(5) << Stack[index].x << " " << Stack[index].y << "\n";
}

int main(){
    readVariables();
    solveProblem();
}