#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;

typedef pair<double, double> point;

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

int n,i,j,pos,dr;
point v[120005];
point s[120005];

double Det(point p1,point p2,point p3){
    return (p2.x - p1.x) * (p3.y - p1.y) - (p3.x - p1.x) * (p2.y - p1.y);
}

bool cmp(point a, point b){
    return Det(v[1],a,b) < 0;
}

void sort_points(){

    pos = 1;

    for (i = 2;i <= n;i++)
        if (v[i] < v[pos])
            pos = i;

    swap(v[1],v[pos]);

    sort(v+2,v+n+1,cmp);
}

void Infasuratoare(){
    sort_points();

    s[1] = v[1];
    s[2] = v[2];

    dr = 2;

    for (i = 3;i <= n;i++){
        while (dr >= 2 && Det(s[dr-1],s[dr],v[i]) > 0)
            dr--;
        s[++dr] = v[i];
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    fin >> n;

    for (i = 1;i <= n;i++)
        fin >> v[i].x >> v[i].y;

    Infasuratoare();

    fout << fixed << dr << "\n";
    for (i = dr;i >= 1;i--)
        fout << setprecision(9) << s[i].x << " " << s[i].y << "\n";

    return 0;
}