Problem: <image>


As shown in the figure above, cut a convex polygon g by a line p1p2 and print the area of the cut polygon which is on the left-hand side of the line.

g is represented by a sequence of points p1, p2,..., pn where line segments connecting pi and pi+1 (1 ≤ i ≤ n−1) are sides of the convex polygon. The line segment connecting pn and p1 is also a side of the polygon.

Constraints

* 3 ≤ n ≤ 100
* 1 ≤ q ≤ 100
* -10000 ≤ xi, yi ≤ 10000
* -10000 ≤ p1x,p1y,p2x,p2y ≤ 10000
* No point in g will occur more than once.
* p1 ≠ p2

Input

The input is given in the following format:


g (the sequence of the points of the polygon)
q (the number of queries = the number of target lines)
1st query
2nd query
:
qth query


g is given as a sequence of points p1,..., pn in the following format:


n
x1 y1
x2 y2
:
xn yn


The first integer n is the number of points. The coordinate of the i-th point pi is given by two integers xi and yi. The coordinates of points are given in the order of counter-clockwise visit of them. Note that all interior angles of given convex polygons are less than or equal to 180.

For each query, a line represented by two points p1 and p2 is given. The coordinates of the points are given by four integers p1x, p1y, p2x and p2y.

Output

For each query, print the area of the cut polygon. The output values should be in a decimal fraction with an error less than 0.00001.

Example

Input

4
1 1
4 1
4 3
1 3
2
2 0 2 4
2 4 2 0


Output

2.00000000
4.00000000

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
#define mm(a,b) memset(a,b,sizeof(a))
#define ACCELERATE (ios::sync_with_stdio(false),cin.tie(0))
#define pii pair<int,int>
#define pdd pair<db,db>
#define pll pair<long long,long long>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define rush() int T;scanf("%d",&T);while(T--)
#define debug(x) cout<<#x<<": "<<x<<endl
#define sc(a) scanf("%d",&a)
#define sc2(a,b) scanf("%d%d",&a,&b)
#define sc3(a,b,c) scanf("%d%d%d",&a,&b,&c)
#define pf(x) printf("%d\n",x)
#define pf2(x,y) printf("%d %d\n",x,y)
#define pf3(x,y,z) printf("%d %d %d\n",x,y,z)
#define all(x) (x).begin(),(x).end()
#define PI acos(-1.0)
#define E exp(1.0)
#define db double
#define ll long long
#define ld long db
#define ull unsigned long long
//#define io
using namespace std;
const int inf=0x3f3f3f3f;
const ll INF=0x3f3f3f3f3f3f3f3f;
//#define gc getchar
//char buf[1<<21],*p1=buf,*p2=buf;
//inline int gc(){return p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++;}
//inline int read()
//{
//    int ret=0,f=0;char c=gc();
//    while(!isdigit(c)){if(c=='-')f=1;c=gc();}
//    while(isdigit(c)){ret=ret*10+c-48;c=gc();}
//    if(f)return -ret;return ret;
//}
const int N=1e2+50;
const db EPS=1e-10;
inline int sign(db a){return a<-EPS?-1:a>EPS;}
inline int cmp(db a,db b){return sign(a-b);}
inline db sqr(db x){return x*x;}
struct Point{
    db x,y;
    Point(){}
    Point(db _x,db _y):x(_x),y(_y){}
    void input(){scanf("%lf%lf",&x,&y);}
    void output(){printf("%.10f %.10f\n",x,y);}
    bool operator == (Point b)const{
        return sign(x-b.x)==0&&sign(y-b.y)==0;
    }
    bool operator < (Point b)const{
        return sign(x-b.x)==0?sign(y-b.y)<0:x<b.x;
    }
    Point operator + (const Point &b)const{
        return Point(x+b.x,y+b.y);
    }
    Point operator - (const Point &b)const{
        return Point(x-b.x,y-b.y);
    }
    db operator ^ (const Point &b)const{
        return x*b.y-y*b.x;
    }
    db operator * (const Point &b)const{
        return x*b.x+y*b.y;
    }
    db len(){return hypot(x,y);}
    db len2(){return x*x+y*y;}
    db distance(Point p){return hypot(x-p.x,y-p.y);}
    Point operator * (const db &k)const{
        return Point(x*k,y*k);
    }
    Point operator / (const db &k)const{
        return Point(x/k,y/k);
    }
    db rad(Point a,Point b){
        Point p=*this;
        return fabs(atan2(fabs((a-p)^(b-p)),(a-p)*(b-p)));
    }
    Point unit(){return *this/len();}
    Point trunc(db r){
        db l=len();
        if(!sign(l))return *this;
        r/=l;
        return Point(x*r,y*r);
    }
    Point rotleft(){return Point(-y,x);}
    Point rotright(){return Point(y,-x);}
    Point rotate(Point p,db angle){
        Point v=(*this)-p;
        db c=cos(angle),s=sin(angle);
        return Point(p.x+v.x*c-v.y*s,p.y+v.x*s+v.y*c);
    }
};
#define cross(p1,p2,p3) ((p2.x-p1.x)*(p3.y-p1.y)-(p3.x-p1.x)*(p2.y-p1.y))
#define crossOp(p1,p2,p3) sign(cross(p1,p2,p3))
struct Line{
    Point s,e;
    Line(){}
    Line(Point _s,Point _e):s(_s),e(_e){}
    bool operator == (Line v){
        return (s==v.s)&&(e==v.e);
    }
    Line(Point p,db angle){
        s=p;
        if(sign(angle-PI/2)==0)e=(s+Point(0,1));
        else e=(s+Point(1,tan(angle)));
    }
    Line(db a,db b,db c){
        if(sign(a)==0){
            s=Point(0,-c/b);e=Point(1,-c/b);
        }else if(sign(b)==0){
            s=Point(-c/a,0);e=Point(-c/a,1);
        }else{
            s=Point(0,-c/b);e=Point(1,(-c-a)/b);
        }
    }
    void input(){s.input();e.input();}
    void adjust(){if(e<s)swap(s,e);}
    db length(){return s.distance(e);}
    //[0,PI)
    db angle(){
        db k=atan2(e.y-s.y,e.x-s.x);
        if(sign(k)<0)k+=PI;
        if(sign(k-PI)==0)k-=PI;
        return k;
    }
    //line|1 on the left|2 on the right|3 on line|
    int relation(Point p){
        int c=sign((p-s)^(e-s));
        if(c<0)return 1;
        else if(c>0)return 2;
        else return 3;
    }
    bool pointonseg(Point p){
        return sign((p-s)^(e-s))==0&&sign((p-s)*(p-e))<=0;
    }
    bool parallel(Line v){
        return sign((e-s)^(v.e-v.s))==0;
    }
    //|0 not intersect|1 non-standard|2 intersect|
    int segcrossseg(Line v){
        int d1=sign((e-s)^(v.s-s));
        int d2=sign((e-s)^(v.e-s));
        int d3=sign((v.e-v.s)^(s-v.s));
        int d4=sign((v.e-v.s)^(e-v.s));
        if((d1^d2)==-2&&(d3^d4)==-2)return 2;
        return (d1==0&&sign((v.s-s)*(v.s-e))<=0)||
            (d2==0&&sign((v.e-s)*(v.e-e))<=0)||
            (d3==0&&sign((s-v.s)*(s-v.e))<=0)||
            (d4==0&&sign((e-v.s)*(e-v.e))<=0);
    }
    //|0 not intersect|1 non-standard|2 intersect|
    int linecrossseg(Line v){
        int d1=sign((e-s)^(v.s-s));
        int d2=sign((e-s)^(v.e-s));
        if((d1^d2)==-2)return 2;
        return (d1==0||d2==0);
    }
    //|0 parallel|1 coincides|2 intersect|
    int linecrossline(Line v){
        if((*this).parallel(v))return v.relation(s)==3;
        return 2;
    }
    //要保证两直线不平行或重合
    Point crosspoint(Line v){
        db a1=(v.e-v.s)^(s-v.s);
        db a2=(v.e-v.s)^(e-v.s);
        return Point((s.x*a2-e.x*a1)/(a2-a1),(s.y*a2-e.y*a1)/(a2-a1));
    }
    db dispointtoline(Point p){
        return fabs((p-s)^(e-s))/length();
    }
    db dispointtoseg(Point p){
        if(sign((p-s)*(e-s))<0||sign((p-e)*(s-e))<0)return min(p.distance(s),p.distance(e));
        return dispointtoline(p);
    }
    //前提是两线段不相交，相交距离就是0了
    db dissegtoseg(Line v){
        return min(min(dispointtoseg(v.s),dispointtoseg(v.e)),min(v.dispointtoseg(s),v.dispointtoseg(e)));
    }
    Point lineprog(Point p){
		return s + ( ((e-s)*((e-s)*(p-s)))/((e-s).len2()) );
	}
	Point symmetrypoint(Point p){
		Point q = lineprog(p);
		return Point(2*q.x-p.x,2*q.y-p.y);
	}
};
struct circle{
    Point p;
    db r;
    circle(){}
    circle(Point _p,db _r):p(_p),r(_r){}
    circle(db _x,db _y,db _r){
        p=Point(_x,_y);r=_r;
    }
    Point point(db a){
        return Point(p.x+r*cos(a),p.y+r*sin(a));
    }
    //三角形的外接圆
    circle(Point a,Point b,Point c){
        Line u=Line((a+b)/2,((a+b)/2)+((b-a).rotleft()));
        Line v=Line((b+c)/2,((b+c)/2)+((c-b).rotleft()));
        p=u.crosspoint(v);
        r=p.distance(a);
    }
    //三角形的内切圆
    circle(Point a,Point b,Point c,bool t){
        Line u,v;
        db m=atan2(b.y-a.y,b.x-a.x),n=atan2(c.y-a.y,c.x-a.x);
        u.s=a;
        u.e=u.s+Point(cos((n+m)/2),sin((n+m)/2));
        m=atan2(a.y-b.y,a.x-b.x),n=atan2(c.y-b.y,c.x-b.x);
        v.s=b;
        v.e=v.s+Point(cos((n+m)/2),sin((n+m)/2));
        p=u.crosspoint(v);
        r=Line(a,b).dispointtoseg(p);
    }
    void input(){
        p.input();
        scanf("%lf",&r);
    }
    void output(){
        printf("%2.f %.2f %.2f\n",p.x,p.y,p,r);
    }
    bool operator == (circle v){
        return (p==v.p)&&sign(r-v.r)==0;
    }
    bool operator < (circle v)const{
        return ((p<v.p)||((p==v.p)&&sign(r-v.r)<0));
    }
    db area(){return PI*r*r;}
    db circumference(){return 2*PI*r;}
    //|0 not|1 on|2 in|
    int relation(Point b){
        db dst=b.distance(p);
        if(sign(dst-r)<0)return 2;
        else if(sign(dst-r)==0)return 1;
        return 0;
    }
    //|0 not|1 on|2 in|
    int relationseg(Line v){
        db dst=v.dispointtoseg(p);
        if(sign(dst-r)<0)return 2;
        else if(sign(dst-r)==0)return 1;
        return 0;
    }
    int relationline(Line v){
        db dst=v.dispointtoline(p);
        if(sign(dst-r)<0)return 2;
        else if(sign(dst-r)==0)return 1;
        return 0;
    }
    //|1 内含|2 内切|3 相交|4 外切|5 相离|
    int relationcircle(circle v){
        db d=p.distance(v.p);
        if(sign(d-r-v.r)>0)return 5;
        if(sign(d-r-v.r)==0)return 4;
        db l=fabs(r-v.r);
        if(sign(d-r-v.r)<0&&sign(d-l)>0)return 3;
        if(sign(d-l)==0)return 2;
        if(sign(d-l)<0)return 1;
    }
    //|0 没有交点|1 一个交点|2 两个交点|
    int pointcrosscircle(circle v,Point &p1,Point &p2){
        int rel=relationcircle(v);
        if(rel==1||rel==5)return 0;
        db d=p.distance(v.p);
        db l=(d*d+r*r-v.r*v.r)/(2*d);
        db h=sqrt(r*r-l*l);
        Point tmp=p+(v.p-p).trunc(l);
        p1 = tmp+((v.p-p).rotleft().trunc(h));
		p2 = tmp+((v.p-p).rotright().trunc(h));
        if(rel==2||rel==4)return 1;
        return 2;
    }
    int pointcrossline(Line v,Point &p1,Point &p2){
        if(!(*this).relationline(v))return 0;
        Point a=v.lineprog(p);
        db d=v.dispointtoline(p);
        d=sqrt(r*r-d*d);
        if(sign(d)==0){
            p1=a;p2=a;
            return 1;
        }
        p1=a+(v.e-v.s).trunc(d);
        p2=a-(v.e-v.s).trunc(d);
        return 2;
    }
    int getcircle(Point a,Point b,db r1,circle &c1,circle &c2){
        circle x(a,r1),y(b,r1);
        int t=x.pointcrosscircle(y,c1.p,c2.p);
        if(!t)return 0;
        c1.r=c2.r=r;
        return t;
    }
    int getcircle(Line u,Point q,db r1,circle &c1,circle &c2){
        db dis=u.dispointtoline(q);
        if(sign(dis-r1*2)>0)return 0;
        if(sign(dis)==0){
            c1.p=q+((u.e-u.s).rotleft().trunc(r1));
            c2.p=q+((u.e-u.s).rotright().trunc(r1));
            c1.r=c2.r=r1;
            return 2;
        }
        Line u1=Line((u.s+(u.e-u.s).rotleft().trunc(r1)),(u.e+(u.e-u.s).rotleft().trunc(r1)));
		Line u2=Line((u.s+(u.e-u.s).rotright().trunc(r1)),(u.e+(u.e-u.s).rotright().trunc(r1)));
		circle cc = circle(q,r1);
		Point p1,p2;
		if(!cc.pointcrossline(u1,p1,p2))cc.pointcrossline(u2,p1,p2);
		c1 = circle(p1,r1);
		if(p1 == p2){
			c2 = c1;
			return 1;
		}
		c2 = circle(p2,r1);
		return 2;
    }
    int getcircle(Line u,Line v,db r1,circle &c1,circle &c2,circle &c3,circle &c4){
        if(u.parallel(v))return 0;//两直线平行
		Line u1=Line(u.s+(u.e-u.s).rotleft().trunc(r1),u.e+(u.e-u.s).rotleft().trunc(r1));
		Line u2=Line(u.s+(u.e-u.s).rotright().trunc(r1),u.e+(u.e-u.s).rotright().trunc(r1));
		Line v1=Line(v.s+(v.e-v.s).rotleft().trunc(r1),v.e+(v.e-v.s).rotleft().trunc(r1));
		Line v2=Line(v.s+(v.e-v.s).rotright().trunc(r1),v.e+(v.e-v.s).rotright().trunc(r1));
		c1.r=c2.r=c3.r=c4.r=r1;
		c1.p=u1.crosspoint(v1);
		c2.p=u1.crosspoint(v2);
		c3.p=u2.crosspoint(v1);
		c4.p=u2.crosspoint(v2);
		return 4;
    }
    int getcircle(circle cx,circle cy,db r1,circle &c1,circle &c2){
		circle x(cx.p,r1+cx.r),y(cy.p,r1+cy.r);
		int t=x.pointcrosscircle(y,c1.p,c2.p);
		if(!t)return 0;
		c1.r=c2.r=r1;
		return t;
	}
	int tangentline(Point q,Line &u,Line &v){
		int x   = relation(q);
		if(x == 2)return 0;
		if(x == 1){
			u = Line(q,q + (q-p).rotleft());
			v = u;
			return 1;
		}
		db d = p.distance(q);
		db l = r*r/d;
		db h = sqrt(r*r-l*l);
		u = Line(q,p + ((q-p).trunc(l) + (q-p).rotleft().trunc(h)));
		v = Line(q,p + ((q-p).trunc(l) + (q-p).rotright().trunc(h)));
		return 2;
	}
	db areacircle(circle v){
		int rel = relationcircle(v);
		if(rel >= 4)return 0.0;
		if(rel <= 2)return min(area(),v.area());
		db d = p.distance(v.p);
		db hf = (r+v.r+d)/2.0;
		db ss = 2*sqrt(hf*(hf-r)*(hf-v.r)*(hf-d));
		db a1 = acos((r*r+d*d-v.r*v.r)/(2.0*r*d));
		a1 = a1*r*r;
		db a2 = acos((v.r*v.r+d*d-r*r)/(2.0*v.r*d));
		a2 = a2*v.r*v.r;
		return a1+a2-ss;
	}
	db areatriangle(Point a,Point b){
		if(sign((p-a)^(p-b)) == 0)return 0.0;
		Point q[5];
		int len = 0;
		q[len++] = a;
		Line l(a,b);
		Point p1,p2;
		if(pointcrossline(l,q[1],q[2])==2){
			if(sign((a-q[1])*(b-q[1]))<0)q[len++] = q[1];
			if(sign((a-q[2])*(b-q[2]))<0)q[len++] = q[2];
		}
		q[len++] = b;
		if(len == 4 && sign((q[0]-q[1])*(q[2]-q[1]))>0)swap(q[1],q[2]);
		db res = 0;
		for(int i = 0;i < len-1;i++){
			if(relation(q[i])==0||relation(q[i+1])==0){
				db arg = p.rad(q[i],q[i+1]);
				res += r*r*arg/2.0;
			}
			else{
				res += fabs((q[i]-p)^(q[i+1]-p))/2.0;
			}
		}
		return res;
	}
};
int getTangents(circle A,circle B,Point *a,Point *b)
{
    int cnt=0;        //存切点用
    if(sign(A.r-B.r)<0){
        swap(A,B);
        swap(a,b);
    }
    db d=sqrt((A.p.x-B.p.x)*(A.p.x-B.p.x)+(A.p.y-B.p.y)*(A.p.y-B.p.y));     //圆心距
    db rdiff=A.r-B.r;      //两圆半径差
    db rsum=A.r+B.r;       //两圆半径和
    if(sign(d-rdiff)<0)return 0;        //1.内含
    db base=atan2(B.p.y-A.p.y,B.p.x-A.p.x);      //向量AB的极角
    if(sign(d)== 0)return -1;        //2.重合
    if(sign(d-rdiff) == 0){       //3.内切
        a[cnt]=b[cnt]=A.point(base);
        cnt++;
        return 1;
    }
    db ang=acos((A.r-B.r)/d);
    a[cnt]=A.point(base+ang);b[cnt]=B.point(base+ang);cnt++;      //4.相交（外切、外离的外公切线也在此求出）
    a[cnt]=A.point(base-ang);b[cnt]=B.point(base-ang);cnt++;      //两条外公切线的切点
    if(sign(d-rsum)==0){        //5.外切
        a[cnt]=b[cnt]=A.point(base);
        cnt++;
    }
    else if(sign(d-rsum)>0){      //6.外离
        db ang=acos((A.r+B.r)/d);
        a[cnt]=A.point(base+ang);b[cnt]=B.point(PI+base+ang);cnt++;
        a[cnt]=A.point(base-ang);b[cnt]=B.point(PI+base-ang);cnt++;
    }
    return cnt;
}
struct polygon{
    int n;
    Point p[N];
    Line l[N];
    void input(int _n){
        n=_n;
        rep(i,0,n-1)p[i].input();
    }
    void add(Point q){p[n++]=q;}
    void getline(){rep(i,0,n-1)l[i]=Line(p[i],p[(i+1)%n]);}
    struct cmp{
		Point p;
		cmp(const Point &p0){p = p0;}
		bool operator()(const Point &aa,const Point &bb){
			Point a = aa, b = bb;
			int d = sign((a-p)^(b-p));
			if(d == 0){
				return sign(a.distance(p)-b.distance(p)) < 0;
			}
			return d > 0;
		}
	};
	//极角排序
	void norm(){
        Point mi=p[0];
        rep(i,1,n-1)mi=min(mi,p[i]);
        sort(p,p+n,cmp(mi));
	}
	//`得到的凸包里面的点编号是[0,n-1]的`
	//`注意如果有影响，要特判下所有点共点，或者共线的特殊情况`
	void getconvex(polygon &convex){
		sort(p,p+n);
		convex.n=n;
		rep(i,0,min(n,2)-1)convex.p[i]=p[i];
		if(convex.n==2&&(convex.p[0]==convex.p[1]))convex.n--;//特判
		if(n<=2)return;
		int &top=convex.n;
		top=1;
		rep(i,2,n-1){
            while(top&&sign((convex.p[top]-p[i])^(convex.p[top-1]-p[i]))<=0)top--;
            convex.p[++top] = p[i];
		}
		int temp=top;
		convex.p[++top]=p[n-2];
		per(i,n-3,0){
            while(top!=temp&&sign((convex.p[top]-p[i])^(convex.p[top-1]-p[i]))<=0)top--;
			convex.p[++top]=p[i];
		}
		if(convex.n==2&&(convex.p[0]==convex.p[1]))convex.n--;//特判
		convex.norm();//`原来得到的是顺时针的点，排序后逆时针`
	}
	//`得到凸包的另外一种方法`
	void Graham(polygon &convex){
		norm();
		int &top=convex.n;
		top=0;
		if(n==1){
			top=1;
			convex.p[0]=p[0];
			return;
		}
		if(n==2){
			top=2;
			convex.p[0]=p[0];
			convex.p[1]=p[1];
			if(convex.p[0]==convex.p[1])top--;
			return;
		}
		convex.p[0]=p[0];
		convex.p[1]=p[1];
		top=2;
		rep(i,2,n-1){
            while(top>1&&sign((convex.p[top-1]-convex.p[top-2])^(p[i]-convex.p[top-2]))<=0)top--;
			convex.p[top++]=p[i];
		}
		if(convex.n==2&&(convex.p[0]==convex.p[1]))convex.n--;//特判
	}
	//`判断是不是凸的`
	bool isconvex(){
		bool s[2];
		memset(s,false,sizeof(s));
		rep(i,0,n-1){
            int j=(i+1)%n;
			int k=(j+1)%n;
			s[sign((p[j]-p[i])^(p[k]-p[i]))+1]=true;
			if(s[0]&&s[2])return false;
		}
		return true;
	}
	//`判断点和任意多边形的关系`
	//|` 0 外部`|` 1 内部`|` 2 边上`|` 3 点上`|
	int relationpoint(Point q){
	    rep(i,0,n-1){
            if(p[i]==q)return 3;
	    }
		getline();
		rep(i,0,n-1){
            if(l[i].pointonseg(q))return 2;
		}
		int cnt=0;
		rep(i,0,n-1){
            int j=(i+1)%n;
			int k=sign((q-p[j])^(p[i]-p[j]));
			int u=sign(p[i].y-q.y);
			int v=sign(p[j].y-q.y);
			if(k>0&&u<0&&v>=0)cnt++;
			if(k<0&&v<0&&u>=0)cnt--;
		}
		return cnt!=0;
	}
    //`直线u切割凸多边形左侧`
	//`注意直线方向`
	void convexcut(Line u,polygon &po){
		int &top = po.n;//注意引用
		top = 0;
		for(int i = 0;i < n;i++){
			int d1 = sign((u.e-u.s)^(p[i]-u.s));
			int d2 = sign((u.e-u.s)^(p[(i+1)%n]-u.s));
			if(d1 >= 0)po.p[top++] = p[i];
			if(d1*d2 < 0)po.p[top++] = u.crosspoint(Line(p[i],p[(i+1)%n]));
		}
	}
	//	//`得到周长`
//	//`测试 LightOJ1239`
	db getcircumference(){
		db sum = 0;
		for(int i = 0;i < n;i++){
			sum += p[i].distance(p[(i+1)%n]);
		}
		return sum;
	}
	//`得到面积`
	db getarea(){
		db sum = 0;
		for(int i = 0;i < n;i++){
			sum += (p[i]^p[(i+1)%n]);
		}
		return fabs(sum)/2;
	}
	//	//`得到方向`
//	//` 1 表示逆时针，0表示顺时针`
	bool getdir(){
		db sum = 0;
		for(int i = 0;i < n;i++)
			sum += (p[i]^p[(i+1)%n]);
		if(sign(sum) > 0)return 1;
		return 0;
	}
	//	//`得到重心`
	Point getbarycentre(){
		Point ret(0,0);
		db area = 0;
		for(int i = 1;i < n-1;i++){
			db tmp = (p[i]-p[0])^(p[i+1]-p[0]);
			if(sign(tmp) == 0)continue;
			area += tmp;
			ret.x += (p[0].x+p[i].x+p[i+1].x)/3*tmp;
			ret.y += (p[0].y+p[i].y+p[i+1].y)/3*tmp;
		}
		if(sign(area)) ret = ret/area;
		return ret;
	}
	//	//`多边形和圆交的面积`
	db areacircle(circle c){
		db ans = 0;
		for(int i = 0;i < n;i++){
			int j = (i+1)%n;
			if(sign( (p[j]-c.p)^(p[i]-c.p) ) >= 0)
				ans += c.areatriangle(p[i],p[j]);
			else ans -= c.areatriangle(p[i],p[j]);
		}
		return fabs(ans);
	}
	//	//`多边形和圆关系`
//	//` 2 圆完全在多边形内`
//	//` 1 圆在多边形里面，碰到了多边形边界`
//	//` 0 其它`
	int relationcircle(circle c){
		getline();
		int x = 2;
		if(relationpoint(c.p) != 1)return 0;//圆心不在内部
		for(int i = 0;i < n;i++){
			if(c.relationseg(l[i])==2)return 0;
			if(c.relationseg(l[i])==1)x = 1;
		}
		return x;
	}
};
//`AB*AC`
db dot(Point A,Point B,Point C){
	return (B-A)*(C-A);
}
//`最小矩形面积覆盖`
//` A 必须是凸包(而且是逆时针顺序)`
db minRectangleCover(polygon A){
	//`要特判A.n < 3的情况`
	if(A.n < 3)return 0.0;
	A.p[A.n] = A.p[0];
	db ans = -1;
	int r = 1, p = 1, q;
	for(int i = 0;i < A.n;i++){
		//`卡出离边A.p[i] - A.p[i+1]最远的点`
		while( sign( cross(A.p[i],A.p[i+1],A.p[r+1]) - cross(A.p[i],A.p[i+1],A.p[r]) ) >= 0 )
			r = (r+1)%A.n;
		//`卡出A.p[i] - A.p[i+1]方向上正向n最远的点`
		while(sign( dot(A.p[i],A.p[i+1],A.p[p+1]) - dot(A.p[i],A.p[i+1],A.p[p]) ) >= 0 )
			p = (p+1)%A.n;
		if(i == 0)q = p;
		//`卡出A.p[i] - A.p[i+1]方向上负向最远的点`
		while(sign(dot(A.p[i],A.p[i+1],A.p[q+1]) - dot(A.p[i],A.p[i+1],A.p[q])) <= 0)
			q = (q+1)%A.n;
		db d = (A.p[i] - A.p[i+1]).len2();
		db tmp = cross(A.p[i],A.p[i+1],A.p[r]) *
			(dot(A.p[i],A.p[i+1],A.p[p]) - dot(A.p[i],A.p[i+1],A.p[q]))/d;
		if(ans < 0 || ans > tmp)ans = tmp;
	}
	return ans;
}
//`直线切凸多边形`
//`多边形是逆时针的，在q1q2的左侧`
//`测试:HDU3982`
vector<Point> convexCut(const vector<Point> &ps,Point q1,Point q2){
	vector<Point>qs;
	int n = ps.size();
	for(int i = 0;i < n;i++){
		Point p1 = ps[i], p2 = ps[(i+1)%n];
		int d1 = sign((q2-q1)^(p1-q1)), d2 = sign((q2-q1)^(p2-q1));
		if(d1 >= 0)
			qs.push_back(p1);
		if(d1 * d2 < 0)
			qs.push_back(Line(p1,p2).crosspoint(Line(q1,q2)));
	}
	return qs;
}
//`半平面交`
//`测试 POJ3335 POJ1474 POJ1279`
//***************************
struct halfplane:public Line{
	db angle;
	halfplane(){}
	//`表示向量s->e逆时针(左侧)的半平面`
	halfplane(Point _s,Point _e){
		s = _s;
		e = _e;
	}
	halfplane(Line v){
		s = v.s;
		e = v.e;
	}
	void calcangle(){
		angle = atan2(e.y-s.y,e.x-s.x);
	}
	bool operator <(const halfplane &b)const{
		return angle < b.angle;
	}
};
struct halfplanes{
	int n;
	halfplane hp[N];
	Point p[N];
	int que[N];
	int st,ed;
	void push(halfplane tmp){
		hp[n++] = tmp;
	}
	//去重
	void unique(){
		int m = 1;
		for(int i = 1;i < n;i++){
			if(sign(hp[i].angle-hp[i-1].angle) != 0)
				hp[m++] = hp[i];
			else if(sign( (hp[m-1].e-hp[m-1].s)^(hp[i].s-hp[m-1].s) ) > 0)
				hp[m-1] = hp[i];
		}
		n = m;
	}
	bool halfplaneinsert(){
		for(int i = 0;i < n;i++)hp[i].calcangle();
		sort(hp,hp+n);
		unique();
		que[st=0] = 0;
		que[ed=1] = 1;
		p[1] = hp[0].crosspoint(hp[1]);
		for(int i = 2;i < n;i++){
			while(st<ed && sign((hp[i].e-hp[i].s)^(p[ed]-hp[i].s))<0)ed--;
			while(st<ed && sign((hp[i].e-hp[i].s)^(p[st+1]-hp[i].s))<0)st++;
			que[++ed] = i;
			if(hp[i].parallel(hp[que[ed-1]]))return false;
			p[ed]=hp[i].crosspoint(hp[que[ed-1]]);
		}
		while(st<ed && sign((hp[que[st]].e-hp[que[st]].s)^(p[ed]-hp[que[st]].s))<0)ed--;
		while(st<ed && sign((hp[que[ed]].e-hp[que[ed]].s)^(p[st+1]-hp[que[ed]].s))<0)st++;
		if(st+1>=ed)return false;
		return true;
	}
	//`得到最后半平面交得到的凸多边形`
	//`需要先调用halfplaneinsert() 且返回true`
	void getconvex(polygon &con){
		p[st] = hp[que[st]].crosspoint(hp[que[ed]]);
		con.n = ed-st+1;
		for(int j = st,i = 0;j <= ed;i++,j++)
			con.p[i] = p[j];
	}
};
vector<Point>g,r;
polygon t;
Point a,b;
int main()
{
    int n;
    sc(n);
    rep(i,1,n){
        db x,y;
        scanf("%lf%lf",&x,&y);
        g.push_back({x,y});
    }
    int q;
    sc(q);
    while(q--){
        r.clear();
        a.input();b.input();
        r=convexCut(g,a,b);
//        cout<<"yes"<<endl;
        t.n=r.size();
        if(t.n==0)printf("%.8f\n",0.0);
        else{
            rep(i,0,r.size()-1){
                t.p[i]=r[i];
            }
            db tt=t.getarea();
            printf("%.8f\n",tt);
        }
    }
    return 0;
}