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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
#define PB push_back
#define MP make_pair
#define LL long long
#define int LL
#define FOR(i,a,b) for(int i = (a); i <= (b); i++)
#define RE(i,n) FOR(i,1,n)
#define REP(i,n) FOR(i,0,(int)(n)-1)
#define R(i,n) REP(i,n)
#define VI vector<int>
#define PII pair<int,int>
#define LD long double
#define FI first
#define SE second
#define st FI
#define nd SE
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())

#define unordered_map __fast_unordered_map
template<class Key, class Value, class Hash = std::hash<Key>>
using unordered_map = __gnu_pbds::gp_hash_table<Key, Value, Hash>;

template<class C> void mini(C &a4, C b4) { a4 = min(a4, b4); }
template<class C> void maxi(C &a4, C b4) { a4 = max(a4, b4); }

template<class TH> void _dbg(const char *sdbg, TH h){ cerr<<sdbg<<'='<<h<<endl; }
template<class TH, class... TA> void _dbg(const char *sdbg, TH h, TA... a) {
  while(*sdbg!=',')cerr<<*sdbg++;
  cerr<<'='<<h<<','; _dbg(sdbg+1, a...);
}

template<class T> ostream &operator<<(ostream& os, vector<T> V) {
  os << "["; for (auto vv : V) os << vv << ","; return os << "]";
}
template<class L, class R> ostream &operator<<(ostream &os, pair<L,R> P) {
  return os << "(" << P.st << "," << P.nd << ")";
}

#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (__VA_ARGS__)
#define cerr if(0)cout
#endif

const LD kEps = 1e-13;
inline bool IsZero(int x) { return x == 0; }
inline bool IsZero(LD x) { return abs(x) < kEps; }

template <typename T>
struct Point {
  T x, y;
  Point operator+(const Point<T> &a) const { return {x + a.x, y + a.y}; }
  Point operator-(const Point<T> &a) const { return {x - a.x, y - a.y}; }
  Point operator*(T coef) const { return {x * coef, y * coef}; }
  T CrossProd(const Point<T> &a) const { return x * a.y - y * a.x; }
  T CrossProd(const Point<T> &a, const Point<T> &b) const {
    return (a - *this).CrossProd(b - *this);
  }
  T DotProd(const Point<T> &a) const { return x * a.x + y * a.y; }
  T SqNorm() const { return x * x + y * y; }
  bool IsZero() const { return ::IsZero(x) && ::IsZero(y); }

  friend ostream &operator<<(ostream &os, const Point<T> &p) {
    return os << "(" << p.x << ", " << p.y << ")";
  }
};

template <typename T>
struct Line {
  Point<T> p[2];

  Point<T> &operator[](int a){ return p[a]; }

  // Z biblioteczki ACM-kowej
  vector<int> LineEqNormInt() { // seems ok
    int A = round(p[1].y - p[0].y); int B = round(p[0].x - p[1].x);
    int C = -(A * p[0].x + B * p[0].y); int gcd = abs(__gcd(A, __gcd(B, C)));
    vector<int> res{A, B, C};
    for (auto& x : res) { x /= gcd; }
    if (A < 0 || (A == 0 && B < 0)) { for (auto& x : res) { x *= -1; } }
    return res;
  }
};

// Z biblioteczki ACM-kowej
namespace ACMLib {

bool InUpper(const Point<LD> &a) {
  if (abs(a.y) > kEps) { return a.y > 0; } return a.x > 0;
}
bool angle_cmp(const Point<LD> &a, const Point<LD> &b) {
  bool u = InUpper(a); bool v = InUpper(b);
  return u!=v ? u : a.CrossProd(b)>0;
}
/** @brief a+(b-a)*f \in c+lin(d-c)  @returns f */
LD cross(const Point<LD> &a, const Point<LD> &b, const Point<LD> &c, const Point<LD> &d) {
  return (d - c).CrossProd(a - c) / (d - c).CrossProd(a - b);
}

struct ClipLine { // valid side is on left
  ClipLine(Point<LD> A, Point<LD> B) : al(A), bl(B), a(A), b(B) {};
  Point<LD> al,bl; // original line points
  mutable Point<LD> a,b; // actual intersection points
  Point<LD> dir() const { return bl - al; }
  bool operator<(const ClipLine& l) const { return angle_cmp(dir(),l.dir()); }
  Point<LD> cross(const ClipLine& l) {
    return al + (bl - al) * ACMLib::cross(al, bl, l.al, l.bl);
  }
  bool left(Point<LD> p) { return (bl - al).CrossProd(p - al) > 0; }
};

struct Clip {
  Clip(LD r) : area(4*r*r) {
    Point<LD> a{-r,-r}, b{r,-r}, c{r,r}, d{-r,r};
    lines = {ClipLine(a,b), ClipLine(b,c), ClipLine(c,d), ClipLine(d,a)};
  }

  map<vector<int>, Line<int>> line_memo;
  
  // doesn't work when two equal lines are inserted
  // in such case create set of normalized equations of lines with custom == kEps
  void insert(Line<int> l) {
    debug(l[0], l[1]);
    auto line_repr = l.LineEqNormInt();
    auto memo_iter = line_memo.find(line_repr);
    if (memo_iter != line_memo.end()) {
      auto prev_line = memo_iter->second;
      auto prev_vec = prev_line[1] - prev_line[0];
      auto cur_vec = l[1] - l[0];
      if (prev_vec.DotProd(cur_vec) < 0) {
        lines.clear();
      }
      return;
    }
    line_memo[line_repr] = l;
    Point<LD> p0{(LD)l[0].x, (LD)l[0].y}, p1{(LD)l[1].x, (LD)l[1].y};
    insert(ClipLine({p0, p1}));
  }
  void insert(ClipLine l) {
    assert(abs(l.dir().SqNorm()) > kEps); find(l);
    while (size() && !l.left(it->a) && !l.left(it->b)) { erase(); }
    if (size()) {
      while (prev(), size() && !l.left(it->a) && !l.left(it->b)) { erase(); }
    }
    if (size() && (!l.left(it->a) || !l.left(it->b))) {
      l.a = l.cross(*it);
      area -= l.a.CrossProd(it->b)*.5; it->b = l.a; next();
      l.b = l.cross(*it);
      if ((l.a-l.b).SqNorm() < kEps) { l.b = l.a; }
      area -= it->a.CrossProd(l.b) * .5;
      it->a = l.b;
      if (!(l.a - l.b).IsZero()) { area += l.a.CrossProd(l.b)*.5; lines.insert(l); }
    }
  }
  void find(const ClipLine &l) {
    it = lines.lower_bound(l); if (it == lines.end()) { it = lines.begin(); }
  }
  void recalculate() {
    area = 0; for (const ClipLine &l : lines) area += l.a.CrossProd(l.b); area *= .5;
  }
  int size() { return lines.size(); }
  void next() { if(++it==lines.end()) it = lines.begin(); }
  void prev() { if(it==lines.begin()) it = lines.end(); --it; }
  void erase() {
    assert(it!=lines.end()); area -= it->a.CrossProd(it->b)*.5; it = lines.erase(it);
    if(it==lines.end()) it = lines.begin();
  }
  typename set<ClipLine>::iterator it; set<ClipLine> lines; LD area;
};
}

int N;
vector<array<Point<int>, 2>> magicians;
vector<Point<int>> all_points;
vector<Line<int>> limit_lines;

int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout << fixed << setprecision(13);
  cerr << fixed << setprecision(6);

  cin >> N;
  magicians.resize(N);
  for (auto &magician : magicians) {
    for (int b : {0, 1}) {
      cin >> magician[b].x >> magician[b].y;
      all_points.push_back(magician[b]);
    }
  }

  const int S = SZ(all_points);
  for (int i = 0; i < S; ++i) {
    for (int j = i + 1; j < S; ++j) {
      const Point<int> &A = all_points[i];
      const Point<int> &B = all_points[j];

      bool can_be_left = true;
      bool can_be_right = true;

      for (const auto &magician : magicians) {
        bool local_can_be_left = false;
        bool local_can_be_right = false;

        for (int side : {0, 1}) {
          const int prod = A.CrossProd(B, magician[side]);
          if (prod >= 0)
            local_can_be_left = true;
          if (prod <= 0)
            local_can_be_right = true;
        }

        can_be_left &= local_can_be_left;
        can_be_right &= local_can_be_right;
      }

      if (can_be_left)
        limit_lines.push_back(Line<int>{{A, B}});
      if (can_be_right)
        limit_lines.push_back(Line<int>{{B, A}});
    }
  }

  ACMLib::Clip clip(1000);

  for (auto &limit_line : limit_lines)
    clip.insert(limit_line);

  clip.recalculate();
  cout << clip.area << "\n";
}