import java.util.*;
import java.io.*;

public class threedprinter_topraj {
	final static double EPS = 1e-7;
	final static int DEBUG = 0;
	
	Scanner sc;
	PrintStream ps;
	
	class Vertex {
		double x, y, z;
		
		public Vertex(double _x, double _y, double _z) {
			x = _x;
			y = _y;
			z = _z;
		}
		
		Vertex sub(Vertex a) {
			return new Vertex(x-a.x, y-a.y, z-a.z);
		}
		
		Vertex add(Vertex a) {
			return new Vertex(x+a.x, y+a.y, z+a.z);
		}

		Vertex div(double d) {
			return new Vertex(x/d, y/d, z/d);
		}
		
		Vertex mul(double d) {
			return new Vertex(x*d, y*d, z*d);
		}
		
		Vertex unit() {
			return div(mag());
		}
		
		double mag() {
			return Math.sqrt(x*x + y*y + z*z);
		}
		
		public String toString() {
			return "(" + x + "," + y + "," + z + ")";
		}
		
	}
	
	class Face {
		Vertex vertices[];
		
		public Face(int _f) {
			vertices = new Vertex[_f];
		}
		
		public String toString() {
			String str = "";
			
			for(Vertex v:vertices) {
				str += v;
			}
			
			return str;
		}
		
	}
	
	//ab X ac
	Vertex cross(Vertex a, Vertex b, Vertex c) {
		return cross(b.sub(a), c.sub(a));
	}
	
	//u X v
	Vertex cross(Vertex u, Vertex v) {
		double x = u.y*v.z - u.z*v.y;
		double y = u.z*v.x - u.x*v.z;
		double z = u.x*v.y - u.y*v.x;
		
		return new Vertex(x, y, z);
	}
	
	//u . v
	double dot(Vertex u, Vertex v) {
		return u.x*v.x + u.y*v.y + u.z*v.z;
	}
	
	boolean IsParallel(Vertex u, Vertex v) {
		Vertex cross = cross(u, v);
		return (cross.mag()<EPS);
	}
	
	boolean IsCoplanarFace(Face face) {
		if(face.vertices.length<3) {
			System.err.printf("Face only has %d edges!\n", face.vertices.length);
			return false;
		}
		
		Vertex cross = cross(face.vertices[0], face.vertices[1], face.vertices[2]);
		for(int i=2;i<face.vertices.length-1;i++) {
			Vertex ncross = cross(face.vertices[0], face.vertices[i], face.vertices[i+1]);
			
			if(!IsParallel(cross, ncross)) {
				return false;
			}
		}
		
		return true;
	}
	
	boolean AreCoplanarFaces(Face faces[]) {
		
		for(Face face:faces) {
			if(!IsCoplanarFace(face)) {
				return false;
			}
		}
		
		return true;
	}

	boolean IsConvex(Face faces[]) {
		return true;
	}
	
	Vertex GetCentroid(Face face) {
		Vertex centroid = new Vertex(0, 0, 0);
		
		for(Vertex v:face.vertices) {
			centroid = centroid.add(v);
		}
		
		centroid = centroid.div(face.vertices.length);
		return centroid;
	}
	
	Vertex GetCentroid(Face faces[]) {
		Vertex centroid = new Vertex(0, 0, 0);
		
		for(Face face:faces) {
			centroid = centroid.add(GetCentroid(face));
		}
		
		centroid = centroid.div(faces.length);
		
		return centroid;
	}
	
	double GetTetVolume(Vertex d, Vertex a, Vertex b, Vertex c) {
		Vertex cross = cross(a, b, c);
		double triangleArea = cross.mag() / 2.0;
		double height = dot(cross.unit(), d.sub(a));
		
		return Math.abs(triangleArea * height / 3.0);
	}
	
	double GetFaceVolume(Vertex centroid, Face face) {
		double volume = 0;
		
		for(int i=1;i<face.vertices.length-1;i++) {
			volume += GetTetVolume(centroid, face.vertices[0], face.vertices[i], face.vertices[i+1]);
		}
		
		if(DEBUG>0) {
			System.out.printf("volume of face = %.3f\n", volume);
		}
		
		return volume;
	}
	
	double ComputeVolume(Face faces[]) {
		double totalVolume = 0;
		
		Vertex centroid = GetCentroid(faces);
		for(Face face:faces) {
			totalVolume += GetFaceVolume(centroid, face);
		}
		
		return totalVolume;
	}
	
	public void doIt() throws Exception {
		sc = new Scanner( System.in );
		ps = System.out; //new PrintStream( new FileOutputStream( "threedprinter.out" ) ); 
		
		while(true) {
			int n = sc.nextInt();
			if(n==0) break;
			
			double totalVolume = 0;
			for(int ni=0;ni<n;ni++) {
			int f = sc.nextInt();
				
				Face faces[] = new Face[f];
				for(int fi=0;fi<f;fi++) {
					int v = sc.nextInt();
					
					faces[fi] = new Face(v);
					for(int vi=0;vi<v;vi++) {
						double x = sc.nextDouble();
						double y = sc.nextDouble();
						double z = sc.nextDouble();
						
						faces[fi].vertices[vi] = new Vertex(x, y, z);
					}
					
					if(DEBUG>0) {
						ps.printf("Face: %s\n",  faces[fi]);
					}
				}
				
				//checks
				if(!AreCoplanarFaces(faces)) {
					System.out.printf("Faces are not coplanar\n");
					System.exit(-1);
				}
				
				if(!IsConvex(faces)) {
					System.out.printf("Polyhedra is not coplanar\n");
				}
				
				double volume = ComputeVolume(faces);
				
				totalVolume += volume;
			}
			
			ps.printf("%.2f\n", totalVolume);
		}
		
	}
	
	public static void main(String args[]) throws Exception {
		(new threedprinter_topraj()).doIt();
	}
	
}