#include <stdio.h>
#include <vector>
#include <math.h>
#include <algorithm>
#define pb push_back

const int maxn = 120000;

using namespace std;

vector<int> VECT;
double X[maxn], Y[maxn];
int N, VER[maxn];

int main()
{
    freopen("infasuratoare.in", "r", stdin);
    freopen("infasuratoare.out", "w", stdout);
    scanf("%d\n", &N);
    X[0] = 1000000000;
    Y[0] = 1000000000;
    for (int i = 1; i <= N; ++i)
        scanf("%lf %lf\n", &X[i], &Y[i]);
    int punct_initial = 0;
    int cur = 0;
    int move = 1;
    for (int i = 1; i <= N; ++i)
        if (X[i] < X[punct_initial])
            punct_initial = i;
    cur = punct_initial;
    double last = 0;
    while (move || punct_initial != cur)
    {
        move = 0;
        VECT.pb(cur);
        double ma = 10000;
        int poznoua = cur;
        for (int i = 1; i <= N; ++i)
        {
            if (VER[i] || i == cur)
                continue;
            double unghi = atan2((X[i] - X[cur]), Y[i] - Y[cur]);
            if (unghi < 0)
                unghi += 2 * M_PI;
            unghi -= last;
            if (unghi < 0)
                unghi += 2 * M_PI;
            if (ma > unghi)
            {
                ma = unghi;
                poznoua = i;
            }
        }
        last = atan2(-(X[cur] - X[poznoua]), -(Y[cur] - Y[poznoua]));
        if (last < 0)
            last += 2 * M_PI;
        cur = poznoua;
        VER[cur] = 1;
    }
    reverse(VECT.begin(), VECT.end());
    printf("%d\n", VECT.size());
    for (unsigned int i = 0; i < VECT.size(); ++i)
        printf("%lf %lf\n", X[VECT[i]], Y[VECT[i]]);
    return 0;
}