#include<iostream>#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>#define eps 1e-7using namespace std;struct Point{    double x,y;    Point(){}    Point(double x,double y):x(x),y(y){}    void input()    {        scanf("%lf %lf",&x,&y);    }};typedef Point Vector;//从程序上，Vector只是Point的别名int dcmp(double x)//控制精度{    if(fabs(x)<eps) return 0;    else return x<0?-1:1;}double toRad(double deg)//角度变为弧度{    return deg/180.0*acos(-1.0);}Vector operator+(Vector A,Vector B)//向量加{    return Vector(A.x+B.x, A.y+B.y);}Vector operator-(Vector A,Vector B)//向量减{    return Vector(A.x-B.x,A.y-B.y);}Vector operator*(Vector A,double p)//向量数乘{    return Vector(A.x*p,A.y*p);}Vector operator/(Vector A,double p)//向量数除{    return Vector(A.x/p,A.y/p);}bool operator<(const Point &A,const Point &B)//两点比较{    return dcmp(A.x-B.x)<0 || (dcmp(A.x-B.x) == 0 && dcmp(A.y-B.y) < 0);}bool operator==(const Point &A, const Point &B)//两点相等{    return dcmp(A.x-B.x) == 0 && dcmp(A.y-B.y) == 0;}struct Line{    Point s,e;    Vector v;    Line(){}    Line(Point s, Point v, int type)://法向量式       s(s),v(v){}    Line(Point s, Point e):s(s),e(e)//两点式    {        v=e-s;    }};double Dot(Vector A,Vector B)//向量点乘,|A|*|B|*cos<A,B>{    return A.x*B.x+A.y*B.y;}double Length(Vector A)//向量模{    return sqrt(Dot(A,A));}double Angle(Vector A,Vector B)//向量夹角{    return acos(Dot(A,B)/Length(A)/Length(B));}double Cross(Vector A,Vector B)//向量叉积{    return A.x*B.y-B.x*A.y;}double Area2(Point A,Point B,Point C)//向量的有向面积，三角形面积的2倍{    return Cross(B-A,C-A);}double Dist(Point A,Point B)//两点之间的距离{    return Length(A-B);}Vector Rotate(Vector A, double rad)//向量逆时针旋转{    return Vector(A.x*cos(rad)-A.y*sin(rad), A.x*sin(rad)+A.y*cos(rad));}Vector Normal(Vector A)//向量单位法向量，前提不是零向量，即左转90度{    double L=Length(A);    return Vector(-A.y/L,A.x/L);}Point GetLineIntersection(Line l1,Line l2)//两直线的交点，调用前确保两条直线有唯一交点{    Point P=l1.s;    Vector v=l1.v;    Point Q=l2.s;    Vector w=l2.v;    Vector u=P-Q;    double t=Cross(w,u)/Cross(v,w);//注意分母不能为0    return P+v*t;}double DistanceToLine(Point P,Line L)//点到直线的距离{    Point A,B;    A=L.s,B=L.e;    Vector v1=B-A,v2=P-A;    return fabs(Cross(v1,v2)/Length(v1));}double DistanceToSegment(Point P,Line L)//点到线段的距离{    Point A,B;    A=L.s,B=L.e;    if(A==B) return Length(P-A);    Vector v1=B-A,v2=P-A,v3=P-B;    if(dcmp(Dot(v1,v2))<0) return Length(v2);    else if(dcmp(Dot(v1,v3)>0)) return Length(v3);    else return fabs(Cross(v1,v2))/Length(v1);}Point GetLineProjection(Point P,Line L)//点在直线上的投影{    Point A,B;    A=L.s,B=L.e;    Vector v=B-A;    return A+v*(Dot(v,P-A)/Dot(v,v));}bool OnSegment(Point p,Line l)//点在线段上包括端点{    Point a1=l.s;    Point a2=l.e;    return dcmp(Cross(a1-p,a2-p))==0 && dcmp(Dist(p,a1)+Dist(p,a2)-Dist(a1,a2))==0;}bool Paralled(Line l1,Line l2)//直线平行{    return dcmp(Cross(l1.e-l1.s,l2.e-l2.s))==0;}bool SegmentProperIntersection(Line l1,Line l2)//线段是否相交{    if(Paralled(l1,l2))        return false;    Point t=GetLineIntersection(l1,l2);    if(OnSegment(t,l1))        return true;    return false;}double PolygonArea(Point *p, int n)//求多边形面积{    double area = 0;    for(int i=1; i<n-1; i++)      area += Cross(p[i]-p[0],p[i+1]-p[0]);    return area/2.0;}int ConvexHull(Point *p,int n,Point *ch)    //求凸包{    sort(p,p+n);    int m=0;    for ( int i = 0; i < n; ++i )    {        while ( m > 1 && Cross( ch[m - 1] - ch[m - 2], p[i] - ch[m - 2] ) <= 0 ) --m;        ch[m++] = p[i];    }    int k = m;    for ( int i = n - 2; i >= 0; --i )    {        while ( m > k && Cross( ch[m - 1] - ch[m - 2], p[i] - ch[m - 2] ) <= 0 ) --m;        ch[m++] = p[i];    }    if ( n > 1 ) --m;    return m;}int main(){        return 0;}