#include <bits/stdc++.h>

#define ldb long double
#define ldb_pair std::pair <ldb, ldb>
#define x  first
#define y second

#define EPS (1e-12)

ldb cross_product(const ldb_pair& A, const ldb_pair& B, const ldb_pair& C) {
    return (B.x - A.x) * (C.y - A.y) - (B.y - A.y) * (C.x - A.x);
}

ldb_pair origin;
inline bool cmp(const ldb_pair& p0, const ldb_pair& p1) {
    return cross_product(origin, p0, p1) < EPS;
}

#define MAXN 120005

int N;
ldb_pair V[MAXN];

void Sortare() {
    int hull_begin = 1;
    for (int i=2; i<=N; ++i)
        if (V[i] < V[hull_begin])
            hull_begin = i;
    std::swap(V[1], V[hull_begin]);
    origin = V[1];
    std::sort(V+2, V+N+1, cmp);
}

std::vector <int> Stack;
void ConvexHull() {
    Stack.push_back(1);
    Stack.push_back(2);

    for (int i=3; i<=N; ++i) {
        while (Stack.size() > 1 && cross_product(V[Stack[Stack.size()-2]], V[Stack[Stack.size()-1]], V[i]) > EPS)
            Stack.pop_back();
        Stack.push_back(i);
    }
}

std::ifstream In ("infasuratoare.in");
std::ofstream Out("infasuratoare.out");

void Citire() {
    In >> N;
    for (int i=1; i<=N; ++i)
        In >> V[i].x >> V[i].y;
}

void Rezolvare() {
    Sortare();
    ConvexHull();

    Out << Stack.size() << '\n';
    Out << std::fixed << std::setprecision(6);
    for (int i = Stack.size()-1; i>=0; --i)
        Out << V[Stack[i]].x << ' ' << V[Stack[i]].y << '\n';
}

int main()
{
    Citire();
    Rezolvare();

    return 0;
}