#include <bits/stdc++.h>

using namespace std;

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

const int Nmax = 120000 + 1;

Point P[Nmax];
Point stiva[Nmax];

int N, top;

double CCW(Point A, Point B, Point C)
{
    return (B.x - A.x) * (C.y - A.y) -
           (B.y - A.y) * (C.x - A.x);
}

bool cmp(const Point A, const Point B)
{
    return CCW(P[1], A, B) < 0;
}

void sortPoints()
{
    int ind = 1;

    for ( int i = 2; i <= N; ++i )
        if ( P[i] < P[ind] )
            ind = i;

    swap(P[1], P[ind]);
    sort(P + 2, P + N + 1, cmp);
}

void convexHull()
{
    stiva[ ++top ] = P[1];
    stiva[ ++top ] = P[2];

    for ( int i = 3; i <= N; ++i )
    {
        while ( top >= 2 && CCW(stiva[top - 1], stiva[top], P[i]) > 0 )
            top--;

        stiva[ ++top ] = P[i];
    }
}

int main()
{
    ifstream in("infasuratoare.in");
    ofstream out("infasuratoare.out");

    ios_base::sync_with_stdio(false);

    in >> N;

    for ( int i = 1; i <= N; ++i )
        in >> P[i].x >> P[i].y;

    sortPoints();
    convexHull();

    out << top << "\n";

    for ( int i = top; i >= 1; i-- )
        out << fixed << setprecision(10) << stiva[i].x << " " << stiva[i].y << "\n";

    return 0;
}