#include <iostream>
#include <cstdio>
#include <vector>
#include <map>

using namespace std;

struct point
   {
      int x, y;

      point(int x, int y)
         : x(x)
         , y(y)
      {}
   };

struct triangle
   {
      triangle() {}
      triangle(int a, int b, int c) {
          pts[0] = a; pts[1] = b; pts[2] = c;}

      int &         operator [] (size_t id)       { return pts[id]; }
      int const &   operator [] (size_t id) const { return pts[id]; }

   private:
      int pts[3];
   };


const int N = 5000;
int n;
vector<point> points;
vector<triangle> all_triangles;
vector<triangle> small_triangles;
vector<vector<int> > g;
map<long long, int> betw;
map<long long, int> tr_id;
bool used[N];
bool canCut[N];
int x, y;
long long curS, needS;
vector<bool> used_tr;
int divide;
double last_point_x;
double last_point_y;
vector<int> chain1;
vector<int> chain2;

int prev(int v) {
    v = (v - 1 + n) % n;
    while (used[v]) {
        v = (v - 1 + n) % n;
    }
    return v;
}

int next(int v) {
    v = (v + 1) % n;
    while (used[v]) {
        v = (v + 1) % n;
    }
    return v;
}

int orientation(point a, point b, point c) {
    long long l = (b.x - a.x) * 1LL * (c.y - a.y);
   long long r = (b.y - a.y) * 1LL * (c.x - a.x);
   long long res = l - r;
   return (res > 0 ? 1 : (res < 0 ? -1 : 0));
}

bool inside_triangle(triangle t, int pt) {
    return
        orientation(points[t[0]], points[t[1]], points[pt]) > 0 &&
        orientation(points[t[1]], points[t[2]], points[pt]) > 0 &&
        orientation(points[t[2]], points[t[0]], points[pt]) > 0;

}

void updCut(int v) {
    int pr = prev(v);
    int ne = next(v);
    if (orientation(points[pr], points[v], points[ne]) < 0) {
        canCut[v] = false;
        return;
    }
    bool ok = true;
    triangle tr(pr, v, ne);
    for (int i = 0; i < n; i++) {
        if (i == pr || i == ne || i == v || used[i])
            continue;
        if (inside_triangle(tr, i)) {
            ok = false;
            break;
        }
    }
    canCut[v] = ok;
}

void pri(triangle t) {
    for (int j = 0; j < 3; j++)
        cout << "(" << points[t[j]].x / 12. << ", " << points[t[j]].y / 12. << ", " << t[j] << ") ";
    cout << endl;
}

int get_betw(int p1, int p2) {
    if (p1 > p2)
        swap(p1, p2);
    long long hash= p1 * 1000000000LL + p2;
    int id = betw[hash];
    if (id == 0) {
        int x = (points[p1].x + points[p2].x) / 2;
        int y = (points[p1].y + points[p2].y) / 2;
        points.push_back(point(x, y));
        betw[hash] = points.size() - 1;
        return points.size() - 1;
    } else {
        return id;
    }
}

void addTr(int p1, int p2, int trId) {
    if (p1 > p2)
        swap(p1, p2);
    long long hash = 1000000000LL * p1 + p2;
    tr_id[hash] += 1 + trId;
}

int addTr_another(int p1, int p2, int trId) {
    if (p1 > p2)
        swap(p1, p2);
    long long hash = 1000000000LL * p1 + p2;
    int xx = tr_id[hash];
    if (xx == trId + 1)
        return -1;
    return xx - trId - 2;
}

bool in_tr(int v, int t) {
    return small_triangles[t][0] == v || small_triangles[t][1] == v || small_triangles[t][2] == v;
}

vector<int> same(int tr1, int tr2) {
    vector<int> res;
    for (int i = 0; i < 3; i++)
        if (in_tr(small_triangles[tr1][i], tr2))
            res.push_back(small_triangles[tr1][i]);
    return res;
}

void printChains() {
    /*
    cout << "chain1: ";
    for (int i = 0; i < chain1.size(); i++) {
        cout << chain1[i] << " ";
    }
    cout << endl;
    cout << "chain2: ";
    for (int i = 0; i < chain2.size(); i++) {
        cout << chain2[i] << " ";
    }
    cout << endl;
    */
}

void dfs(int v, int p) {
    //cout << "here " << v << endl;
    used_tr[v] = true;
    triangle t = small_triangles[v];
    point p1 = points[t[0]];
    point p2 = points[t[1]];
    point p3 = points[t[2]];
    long long addS = 0;
    addS += (p1.x - p2.x) * 1LL * (p1.y + p2.y) / 2;
    addS += (p2.x - p3.x) * 1LL * (p3.y + p2.y) / 2;
    addS += (p3.x - p1.x) * 1LL * (p1.y + p3.y) / 2;
    if (addS < 0)
        addS = -addS;
    //cout << "S = " << addS + curS << endl;
    if (addS + curS >= needS) {
        used_tr[v] = false;
        for (int i = 0; i < 3; i++) {
            int p11 = t[i];
            int p22 = t[(i + 1) % 3];
            int anoth = addTr_another(p11, p22, v);
            if (anoth != g[v][0] && anoth != g[v][1]) {
                divide = i;
                long long ostS = needS - curS;
                double divide_pr = ostS / (0.0 + addS);
                if (small_triangles[p][0] == p22 || small_triangles[p][1] == p22 || small_triangles[p][2] == p22)
                    swap(p11, p22);
                point _p11 = points[p11];
                point _p22 = points[p22];
                last_point_x = _p11.x + (_p22.x - _p11.x) * divide_pr;
                last_point_y = _p11.y + (_p22.y - _p11.y) * divide_pr;
                //cout << "last is " << last_point_x / 2. << " " << last_point_y / 2. << endl;
                vector<int> sam = same(v, p);
                chain1.push_back(sam[0]);
                chain2.push_back(sam[1]);
                //cout << "last_points are " << points[sam[0]].x / 2 << " " << points[sam[0]].y  / 2<< " " << points[sam[1]].x / 2 << " " << points[sam[1]].y / 2 << endl;
                break;
            }
        }
    return;
    }
    for (int i = 0; i < g[v].size(); i++) {
        int to = g[v][i];
        if (used_tr[to])
            continue;
        curS += addS;
        dfs(to, v);
        //cout << "out to " << v << " " << p << endl;
        if (p != -1) {
            int diff = t[0] + t[1] + t[2] - chain1[chain1.size() - 1] - chain2[chain2.size() - 1];
            // << "points are " << t[0] << " " << t[1] << " " << t[2] << "; chain ends with " << chain1[chain1.size() - 1] << " " << chain2[chain2.size() - 1] << endl;
            //cout << "add point " << points[diff].x / 2. << " " << points[diff].y / 2 << " to chain" << endl;
            if (in_tr(chain1[chain1.size() - 1], p))
                chain2.push_back(diff); else
                chain1.push_back(diff);
            //printChains();
        }
        return;
    }
}

void priv(int v) {
    printf("%d %d (point id = %d)\n", points[v].x , points[v].y, v);
}

void priv(double x, double y) {
    printf("%.18f %.18f", x , y);
}

void privReal(int v) {
    printf("%.18f %.18f\n", ((double) points[v].x) / 12.0, ((double)points[v].y) / 12.0);
}

void privReal(double x, double y) {
    printf("%.18f %.18f\n", x / 12.0, y / 12.0);
}

void out(int k) {
    triangle t = small_triangles[k];
    //cout << t[0] << " " << t[1] << " " << t[2] << endl;
    int diff = t[0] + t[1] + t[2] - chain1[chain1.size() - 1] - chain2[chain2.size() - 1];
    for (int i = 0; i < chain2.size(); i++) {
        if (chain2[i] == diff) {
            while (chain2.size() != i)
                chain2.pop_back();
        }
    }
    printf("%d\n", chain1.size() + chain2.size() + 2);
    //cout << "out figure!!!!!!!!!!!!!!!!!!" << endl;

    privReal(diff);
    for (int i = 0; i < chain1.size(); i++) {
        privReal(chain1[chain1.size() - 1 - i]);
    }
    privReal(last_point_x, last_point_y);
    for (int i = 0; i < chain2.size(); i++) {
        privReal(chain2[i]);
    }
}

int main() {
    freopen("kingdom.in", "r", stdin);
    freopen("kingdom.out", "w", stdout);
    scanf("%d", &n);
    for (int i  = 0; i < n; i++) {
        scanf("%d%d", &x, &y);
        points.push_back(point(x * 12, y * 12));
    }
    for (int i = 0; i < n; i++)
        used[i] = false;
    for (int i = 0; i < n; i++) {
        updCut(i);
    }
    for (int it = 0; it < n - 2; it++) {
        int rem = -1;
        for (int i= 0; i < n; i++) {
            if (!used[i] && canCut[i]) {
                rem = i;
            }
        }
        if (rem == -1) {
            cout << "fail, really" <<endl;
            return 1;
        }

        int pr = prev(rem);
        int ne = next(rem);
        used[rem] = true;
        all_triangles.push_back(triangle(pr, rem, ne));
        updCut(pr);
        updCut(ne);
    }
    //cout << "----\n";
    //cout<<all_triangles.size() << endl;
    //for (int i = 0; i < all_triangles.size(); i++) {
    //  triangle t = all_triangles[i];
        //pri(t);
    //}
    //cout << "----\n";
    for (int i = 0; i < all_triangles.size(); i++) {
        triangle t = all_triangles[i];
        int m1 = get_betw(t[0], t[1]);
        int m2 = get_betw(t[1], t[2]);
        int m3 = get_betw(t[2], t[0]);
        int xx = (points[t[0]].x + points[t[1]].x + points[t[2]].x) / 3;
        int yy = (points[t[0]].y + points[t[1]].y + points[t[2]].y) / 3;
        int med = points.size();
        points.push_back(point(xx, yy));
        small_triangles.push_back(triangle(t[0], m1, med));
        small_triangles.push_back(triangle(t[1], m1, med));
        small_triangles.push_back(triangle(t[1], m2, med));
        small_triangles.push_back(triangle(t[2], m2, med));
        small_triangles.push_back(triangle(t[2], m3, med));
        small_triangles.push_back(triangle(t[0], m3, med));
    }
    for (int i = 0; i < small_triangles.size(); i++) {
        vector<int> tmp;
        g.push_back(tmp);
        triangle t = small_triangles[i];
        addTr(t[0], t[1], i);
        addTr(t[1], t[2], i);
        addTr(t[2], t[0], i);
    }
    for (int i = 0; i < small_triangles.size(); i++) {
        triangle t = small_triangles[i];
        int getAn = addTr_another(t[0], t[1], i);
        if (getAn == -1) {
            int get_an2 = addTr_another(t[1], t[2], i);
            g[i].push_back(get_an2);
        } else {
            g[i].push_back(getAn);
        }
        int getAn3 = addTr_another(t[2], t[0], i);
        g[i].push_back(getAn3);
    }
    //cout << "!!!" << endl;
    //for (int i = 0; i < small_triangles.size(); i++) {
    //  pri(small_triangles[i]);
    //}
    //for (int i = 0; i < small_triangles.size(); i++) {
    //  for (int j = 0; j < g[i].size(); j++) {
    //      cout << g[i][j] << " ";
//      }
    //  cout << endl;
//  }
    //cout << "@@@\n";
    needS = 0;
    for (int i = 0; i < n; i++) {
        point p1 = points[i];
        point p2 = points[(i + 1) % n];
        needS += (p1.x - p2.x) * 1LL * (p1.y + p2.y) / 4;
    }
    //cout << needS << endl;
    for (int i = 0; i < small_triangles.size(); i++) {
        used_tr.push_back(false);
    }
    curS = 0;
    //cout << "ALL POINTS:::::::::::::::::" << endl;
    //for (int i= 0; i < points.size(); i++) {
    //  cout << i << ": " << points[i].x  / 2. << " " << points[i].y /2. << endl;
    //}
    //cout << "END ALL POINTS::::::::::::::::::" << endl;
    dfs(0, -1);
    //cout << "out from dfs" << endl;
    out(0);
    //cout << "end first part" << endl;
    chain1.clear();
    chain2.clear();
    curS = 0;
    dfs(g[0][1], -1);
    out(g[0][1]);
}