> #include<algorithm>
> #include<iostream>
> #include<iomanip>
> #include<cstring>
> #include<cstdlib>
> #include<vector>
> #include<cstdio>
> #include<cmath>
> #include<queue>
> using namespace std;
> inline const int Get_Int() {
> 	int num=0,bj=1;
> 	char x=getchar();
> 	while(x<'0'||x>'9') {
> 		if(x=='-')bj=-1;
> 		x=getchar();
> 	}
> 	while(x>='0'&&x<='9') {
> 		num=num*10+x-'0';
> 		x=getchar();
> 	}
> 	return num*bj;
> }
> const double eps=1e-8;
> int DoubleCompare(double x) { //精度三出口判断与0关系
> 	if(fabs(x)<eps)return 0; //=0
> 	else if(x<0)return -1; //<0
> 	else return 1; //>0
> }
> struct Point {
> 	double x,y;
> 	Point(double _x,double _y):x(_x),y(_y){}
> 	Point(){}
> 	Point operator + (const Point& a) const {
> 		return Point(x+a.x,y+a.y);
> 	}
> 	Point operator - (const Point& a) const {
> 		return Point(a.x-x,a.y-y);
> 	}
> 	Point operator * (const double a) const {
> 		return Point(x*a,y*a);
> 	}
> } ;
> typedef Point Vector;
> double Cross(Vector a,Vector b) { //叉积
> 	return a.x*b.y-b.x*a.y;
> }
> double Area(Point a,Point b,Point c) { //三点的平行四边形有向面积
> 	Vector u=b-a,v=c-a;
> 	return Cross(u,v);
> }
> double Area(int n,Point* P) { //计算多边形有向面积（剖分法） 
> 	double ans=0;
> 	for(int i=2; i<n; i++)ans+=Area(P[1],P[i],P[i+1]);
> 	return ans/2;
> }
> struct Line { //有向直线，左边为半平面
> 	Point p; //直线上任意一点
> 	Vector v; //方向向量
> 	double ang;
> 	Line() {}
> 	Line(Point p,Vector v):p(p),v(v) {
> 		ang=atan2(v.y,v.x);
> 	}
> 	bool operator < (const Line& L) const {
> 		return ang<L.ang;
> 	}
> };
> bool OnLeft(Line L,Point p) { //判断点p是否在有向直线L左边（若不舍直线上的点则加上等号） 
> 	return DoubleCompare(Cross(L.v,L.p-p))>=0;
> }
> Point GetIntersection(Line a,Line b) {
> 	Vector u=a.p-b.p;
> 	double t=Cross(u,b.v)/Cross(a.v,b.v);
> 	return a.p+a.v*t;
> }
> int HalfplaneIntersection(int n,Line* L,Point* poly) {
> 	sort(L+1,L+n+1); //极角排序
> 	int first=1,last=1;
> 	Point p[n+5];
> 	Line q[n+5];
> 	q[last]=L[1];
> 	for(int i=2; i<=n; i++) {
> 		while(first<last&&!OnLeft(L[i],p[last-1]))last--;
> 		while(first<last&&!OnLeft(L[i],p[first]))first++;
> 		q[++last]=L[i];
> 		if(fabs(Cross(q[last].v,q[last-1].v))<eps) { //平行同向，取内侧 
> 			last--;
> 			if(!OnLeft(L[i],p[last-1]))q[last]=L[i];
> 		}
> 		if(first<last)p[last-1]=GetIntersection(q[last-1],q[last]);
> 	}
> 	while(first<last&&!OnLeft(q[first],p[last-1]))last--; //删除无用平面
> 	if(last-first<=1)return 0; //空集
> 	p[last]=GetIntersection(q[last],q[first]);
> 	int m=0;
> 	for(int i=first; i<=last; i++)poly[++m]=p[i]; 
> 	return m; 
> }
> ///////////////
> Point a[10005],p[10005];
> Line l[10005];
> int n,m,sum=0,k;
> int main() {
> 	k=Get_Int();
> 	while(k--) {
> 		scanf("%d",&n);
> 		sum=0;
> 		for(int i=1; i<=n; i++)scanf("%lf%lf",&p[i].x,&p[i].y);
> 		l[++sum]=Line(p[1],p[1]-p[n]);
> 		for(int i=2; i<=n; i++)l[++sum]=Line(p[i],p[i]-p[i-1]);
> 		int cnt=HalfplaneIntersection(sum,l,p);
> 		printf("%0.2lf\n",fabs(Area(cnt,p)));
> 	}
> 	return 0;
> }