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#include<bits/stdc++.h>
using namespace std;
#ifndef d
#define d(...)
#endif
#define st first
#define nd second
#define pb push_back
#define siz(c) (int)(c).size()
#define all(c) (c).begin(), (c).end()
typedef long long LL;
typedef long double LD;
constexpr int INF=1e9+7;
constexpr LL INFL=1e18;
template<class L, class R> ostream &operator<<(ostream &os, pair<L,R> P) {
  return os << "(" << P.st << "," << P.nd << ")";
}

constexpr LD eps=1e-11;

struct point {
	LD x,y;
	point(LD x=0,LD y=0):x(x),y(y){}
	bool isZero() const {
		return max(abs(y),abs(x))<eps;
	}
	bool inUpper() const {
		return (y==0?x:y)>0;
	}
	LD operator ^ (const point& b) const {
		return x*b.y-y*b.x;
	}
	LD operator * (const point& b) const {
		return x*b.x + y*b.y;
	}
	point operator * (const LD c) const {
		return point(x*c,y*c);
	}
	point operator + (const point& b) const {
		return point(x+b.x,y+b.y);
	}
	point operator - () const {
		return point(-x,-y);
	}
	point operator -(const point& b) const {
		return (*this)+(-b);
	}
	bool operator < (const point& b) const {
		if(isZero())
			return !b.isZero();
		if(inUpper()!=b.inUpper())
			return inUpper();
		return ((*this)^b)>0;
	}
	bool operator == (const point& b) const {
		return ((*this)+(-b)).isZero();
	}
	LD val() const {
		return (*this)*(*this);
	}
	friend istream& operator >> (istream& in, point& P) {
		in >> P.x >> P.y;
		return in;
	}
	friend ostream& operator << (ostream& out, const point P) {
		out << "(" << P.x << ", "<< P.y << ")";
		return out;
	}
};

constexpr int maxn=102;

int n;
point mag[maxn*2];

struct line {
	point p[2];
	line(const point x, const point y) {
		p[0]=x,p[1]=y;
	}
	point df() const {
		return p[1]+(-p[0]);
	}
	point& operator[](int a) {
		return p[a];
	}
	bool on(const point x) const {
		return (x^(p[1]+(-p[0])))<eps;
	}
	point proj(const point& x) {
		auto diff=df();
		return p[0]+diff*((diff*(x+(-p[0])))/(diff*diff));
	}
	friend bool parallel(const line& a,const line& b) {
		return abs(a.df()^b.df())<eps;
	}
	friend point intersect(line& a, line& b) {
		assert(not parallel(a,b));
		point vec_a=a.df(), vec_b1=b[1]+(-a[0]), vec_b0=b[0]+(-a[0]);
		LD tr_area = vec_b1^vec_b0;
		LD quad_area = (vec_b1^vec_a) + (vec_a^vec_b0);
		return a[0]+vec_a*(tr_area/quad_area);
	}
};

vector<line>ogr;

LD cross(const point a,const point b) {
	return a^b;
}

LD dblcmp(const LD x) {
	if(abs(x)<eps) return 0;
	return x;
}


point isLL(point a, point b, point c, point d) {
	point p1 = b - a, p2 = d - c;
	long double a1 = p1.y, b1 = -p1.x, c1;
	long double a2 = p2.y, b2 = -p2.x, c2;
	if (dblcmp(a1 * b2 - a2 * b1) == 0) return point(0,0);
	else {
		c1 = a1 * a.x + b1 * a.y;
		c2 = a2 * c.x + b2 * c.y;
		return point((c1 * b2 - c2 * b1) / (a1 * b2 - a2 * b1), (c1 * a2 - c2 * a1) / (b1 * a2 - b2 * a1));
	}
}

struct hp_t {
	point p1, p2;
	long double a;
	hp_t() {}
	hp_t(point tp1, point tp2) : p1(tp1), p2(tp2) {
		tp2 = tp2 - tp1;
		a = atan2(tp2.y, tp2.x);
	}
	bool operator==(const hp_t &r) const {
		return dblcmp(a - r.a) == 0;
	}
	bool operator<(const hp_t &r) const {
		if (dblcmp(a - r.a) == 0) return dblcmp(cross(r.p2 - r.p1, p2 - r.p1)) >= 0;
		else return a < r.a;
	}
} hp[maxn*maxn*4];

int cnt;
constexpr int maxd=400000;

void addhp(point p1, point p2) {
	hp[++cnt] = hp_t(p1, p2);
}

void init() {
	cnt = 0;
	addhp(point(-maxd, -maxd), point(maxd, -maxd));
	addhp(point(maxd, -maxd), point(maxd, maxd));
	addhp(point(maxd, maxd), point(-maxd, maxd));
	addhp(point(-maxd, maxd), point(-maxd, -maxd));
}

bool checkhp(hp_t h1, hp_t h2, hp_t h3) {
	point p = isLL(h1.p1, h1.p2, h2.p1, h2.p2);
	return dblcmp(cross(p - h3.p1, h3.p2 - h3.p1)) > 0;
}

vector<point> hp_inter() {
	sort(hp + 1, hp + 1 + cnt);
	cnt = unique(hp + 1, hp + 1 + cnt) - hp - 1;
	deque<hp_t> DQ;
	DQ.push_back(hp[1]);
	DQ.push_back(hp[2]);
	for (int i = 3; i <= cnt; ++i) {
		while (DQ.size() > 1 && checkhp(*----DQ.end(), *--DQ.end(), hp[i])) DQ.pop_back();
		while (DQ.size() > 1 && checkhp(*++DQ.begin(), *DQ.begin(), hp[i])) DQ.pop_front();
		DQ.push_back(hp[i]);
	}
	while (DQ.size() > 1 && checkhp(*----DQ.end(), *--DQ.end(), DQ.front())) DQ.pop_back();
	while (DQ.size() > 1 && checkhp(*++DQ.begin(), *DQ.begin(), DQ.back())) DQ.pop_front();
	DQ.push_front(DQ.back());
	vector<point> res;
	while (DQ.size() > 1) {
		hp_t tmp = DQ.front();
		DQ.pop_front();
		res.push_back(isLL(tmp.p1, tmp.p2, DQ.front().p1, DQ.front().p2));
	}
	return res;
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	
	//cout<<(dblcmp(0.000000001)==0)<<endl;
	
	cin>>n;
	for(int i=0;i<n;i++) {
		cin>>mag[2*i]>>mag[2*i+1];
	}
	for(int i=0;i<2*n;i++) 
		for(int j=i+1;j<2*n;j++) {
			auto p=mag[i], q=mag[j];
			line l(point(-p.y,p.x),point(-q.y,q.x));
			//cerr<<"rzuty na linie: "<<l[0]<<" --> "<<l[1]<<endl;
			LD mn=INF,mx=-INF;
			for(int m=0;m<n;m++) {
				auto a=l.proj(mag[2*m]), b=l.proj(mag[2*m+1]);
				//cerr<<"rzuty maga: "<<m<<": "<<a<<" "<<b<<endl;
				LD ax,bx;
				if(abs((l.df()).y) < eps) {
					ax=(a.x-l[0].x)/(l[1].x-l[0].x);
					bx=(a.x-l[0].x)/(l[1].x-l[0].x);
				}
				else {
					ax=(a.y-l[0].y)/(l[1].y-l[0].y);
					bx=(b.y-l[0].y)/(l[1].y-l[0].y);
				}
				//cerr<<"ax,bx: "<<ax<<" "<<bx<<endl;
				mx=max(mx,min(ax,bx));
				mn=min(mn,max(ax,bx));
			}
			//cerr<<"mn,mx: "<<mn<<" "<<mx<<endl;
			ogr.emplace_back(l[0]+l.df()*mn,l[0]+(l.df()*mn)+q-p);
			//cerr<<"WPROWADZONO WEKTOREK: "<<ogr.back()[0]<<" --> "<<ogr.back()[1]<<endl;
			ogr.emplace_back(l[0]+l.df()*mx,l[0]+(l.df()*mx)+p-q);
			//cerr<<"WPROWADZONO WEKTOREK: "<<ogr.back()[0]<<" --> "<<ogr.back()[1]<<endl;
		}
	cout<<fixed<<setprecision(20);
	init();
	for(auto& l:ogr) {
		addhp(l[0],l[1]);
	}
	auto hull=hp_inter();
	if(siz(hull)<3) {
		cout<<0.0<<"\n";
		return 0;
	}
	LD res=0;
	for(int i=1;i<=siz(hull);i++)
		res+=hull[i-1]^hull[i%siz(hull)];
	
	cout<<fixed<<setprecision(20)<<abs(res)/2<<"\n";
}