#include <bits/stdc++.h>

using namespace std;

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

const int NMAX = 120005;
const long long INF = (1<<29);

struct punct
{
    long double x,y;
};

punct v[NMAX],pct[NMAX];

long double panta(punct a,punct b,punct c)
{
    return (b.x-a.x)*(c.y-a.y)-(c.x-a.x)*(b.y-a.y);
}

bool cmp2(punct a,punct b)
{
    return panta(v[1],a,b)>=0;
}

bool cmp1(punct a,punct b)
{
    if(a.y==b.y) return a.x<b.x;
    return a.y<b.y;
}

int main()
{
    long long n;
    fin >> n;
    for(long long i=1;i<=n;i++) fin >> v[i].x >> v[i].y;
    sort(v+1,v+n+1,cmp1);
    sort(v+2,v+n+1,cmp2);
    pct[1]=v[1];
    pct[2]=v[2];
    long long sz=2;
    for(long long i=3;i<=n;i++)
    {
        while(sz>=2 and panta(pct[sz-1],pct[sz],v[i])<0)
            sz--;
        pct[++sz]=v[i];
    }
    fout << sz << '\n';
    for(long long i=1;i<=sz;i++)
    {
        fout << fixed << setprecision(13) << pct[i].x << ' ' << pct[i].y << '\n';
    }
    //for(long long i=1;i<=n;i++) fout << v[i].x << ' ' << v[i].y << '\n';
    return 0;
}