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#include <bits/stdc++.h>
using namespace std;
const long double eps=1e-8;
const double pi=acos(-1.0);
int sgn(double x) {
if(fabs(x)<eps)
return 0;
return x<0?-1:1;
}
int dcmp(double x,double y) {
if(fabs(x-y)<eps)
return 0;
return x<y?-1:1;
}
struct Point {
double x,y;
Point() {};
Point(double x,double y):x(x),y(y) {}
Point operator + (Point b) {
return Point(x+b.x,y+b.y);
}
Point operator -(Point b) {
return Point(x-b.x,y-b.y);
}
Point operator *(double k) {
return Point(x*k,y*k);
}
Point operator /(double k) {
return Point(x/k,y/k);
}
bool operator ==(Point b) {
return sgn(x-b.x)==0&&sgn(y-b.y)==0;
}
bool operator <(Point b) {
return sgn(x-b.x)<0||(sgn(x-b.x)==0&&sgn(y-b.y)<0);
}
} now[1000],nex[1000],over[1000],res[1000];
typedef Point Vector;
double dot(Vector A,Vector B) { //点积
return A.x*B.x+A.y*B.y;
}
double Cross(Vector a,Vector b) { //叉积
return a.x*b.y-a.y*b.x;
}
bool cmp(Point r,Point t) { //极角排序
Point tt=t-res[0];
Point rr=r-res[0];
if(sgn(Cross(rr,tt))==0)
return (rr.x*rr.x+rr.y*rr.y)<(tt.x*tt.x+tt.y*tt.y);
return sgn(Cross(rr,tt))>0;
}
struct Line {
Point p1,p2;
Line() {};
Line(Point p1,Point p2):p1(p1),p2(p2) {}
};
typedef Line segment;
bool Point_on_seg(Point p,Line v) { //点和线段的关系，0为点在线段上，1为点在线段上
return sgn(Cross(p-v.p1,v.p2-v.p1))==0&&sgn(dot(p-v.p1,p-v.p2))<=0;
}
Point Cross_Point(Point a,Point b,Point c,Point d) { //两条直线的焦点
double s1=Cross(b-a,c-a);
double s2=Cross(b-a,d-a);
return Point(c.x*s2-d.x*s1,c.y*s2-d.y*s1)/(s2-s1);//先要判断两条是否平行或者重合
}
bool cross_segment(Point a,Point b,Point c,Point d) {
double c1=Cross(b-a,c-a),c2=Cross(b-a,d-a);
double d1=Cross(d-c,a-c),d2=Cross(d-c,b-c);
return sgn(c1)*sgn(c2)<0&&sgn(d1)*sgn(d2)<0;//1相交，0不相交
}
bool Point_in_polygon(Point pt,Point *p,int n) {//1在多边形内部或者边界 0表示在外面
for(int i=0; i<n; i++) {
if(p[i]==pt)
return 1;
}
for(int i=0; i<n; i++) {
Line v=Line(p[i],p[(i+1)%n]);
if(Point_on_seg(pt,v))
return 1;
}
int num=0;
for(int i=0; i<n; i++) {
int j=(i+1)%n;
int c=sgn(Cross(pt-p[j],p[i]-p[j]));
int u=sgn(p[i].y-pt.y);
int v=sgn(p[j].y-pt.y);
if(c>0&&u<0&&v>=0)
num++;
if(c<0&&u>=0&&v<0)
num--;
}
return num!=0;
}
int main() {
// freopen("in.txt","r",stdin);
int t;
scanf("%d",&t);
int lenow;
for(int i=1; i<=t; i++) {
int n;
scanf("%d",&n);
for(int j=0; j<n; j++) {
scanf("%lf%lf",&nex[j].x,&nex[j].y);
}
// res[0]=nex[0];
//sort(nex,nex+n,cmp);
if(i==1) {
for(int j=0; j<n; j++) {
now[j]=nex[j];
}
lenow=n;
} else {
int cnt=0;
for(int j=0; j<lenow; j++) {
for(int w=0; w<n; w++) {
if(cross_segment(now[j],now[(j+1)%lenow],nex[w],nex[(w+1)%n])) {
over[cnt++]=Cross_Point(now[j],now[(j+1)%lenow],nex[w],nex[(w+1)%n]);
//cout<<now[j].x<<" "<<now[j].y<<" "<<now[(j+1)%lenow].x<<" "<<now[(j+1)%lenow].y<<" ";
// cout<<nex[w].x<<" "<<nex[w].y<<" "<<nex[(w+1)%n].x<<" "<<nex[(w+1)%n].y<<" "<<over[cnt-1].x<<" "<<over[cnt-1].y<<" "<<endl;
}
}
}
int tot=0;
for(int j=0; j<lenow; j++) {
if(Point_in_polygon(now[j],nex,n)&&Point_in_polygon(now[j],now,lenow)) {
//cout<<"*"<<now[j].x<<" "<<now[j].y<<endl;
res[tot++]=now[j];
}
}
for(int j=0; j<n; j++) {
if(Point_in_polygon(nex[j],nex,n)&&Point_in_polygon(nex[j],now,lenow)) {
// cout<<"**"<<nex[j].x<<" "<<nex[j].y<<endl;
res[tot++]=nex[j];
}
}
for(int j=0; j<cnt; j++) {
if(Point_in_polygon(over[j],nex,n)&&Point_in_polygon(over[j],now,lenow)) {
// cout<<"***"<<over[j].x<<" "<<over[j].y<<endl;
res[tot++]=over[j];
}
}
if(tot<=2) {
printf("0.000
");
return 0;
} else {
sort(res+1,res+tot,cmp);
for(int j=0; j<tot; j++) {
now[j]=res[j];
//cout<<now[j].x<<" "<<now[j].y<<endl;
}
lenow=tot;
}
}
// scanf("%d",)
}
double ans=0;
for(int i=0; i<lenow; i++) {
//cout<<now[i].x<<" "<<now[i].y<<" "<<ans<<endl;
ans+=Cross(now[i],now[(i+1)%lenow]);
}
printf("%.3f
",0.5*ans);
return 0;
}
