#include <bits/stdc++.h>

using namespace std;

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

const int Nmax = 120005;

int n, top;
int st[Nmax];
pair <double, double> pct[Nmax];
bitset <Nmax> viz;

inline double side(int a, int b, int c)
{
    return pct[c].second * (pct[a].first - pct[b].first) +
            pct[c].first * (pct[b].second - pct[a].second) +
            pct[a].second * pct[b].first - pct[a].first * pct[b].second;
}

int main()
{
    fin >> n;
    for(int i = 1; i <= n; i++)
        fin >> pct[i].second >> pct[i].first;

    sort(pct + 1, pct + n + 1);

    st[1] = 1;
    st[2] = 2;
    top = 2;
    viz[2] = 1;

    for(int i = 3; i <= n; i++)
    {
        while(top >= 2 && side(st[top - 1], st[top], i) < 0)
        {
            viz[st[top]] = 0;
            top--;
        }

        st[++top] = i;
        viz[i] = 1;
    }

    for(int i = n - 1; i >= 1; i--)
        if(!viz[i])
        {
            while(top >= 2 && side(st[top - 1], st[top], i) < 0)
            {
                viz[st[top]] = 0;
                top--;
            }

            st[++top] = i;
            viz[i] = 1;
        }


    fout << top - 1 << "\n";

    fout << fixed << setprecision(12);
    for(int i = 1; i < top; i++)
        fout << pct[st[i]].second << " " << pct[st[i]].first << "\n";

    fin.close();
    fout.close();
    return 0;
}