#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;

#define MAXN 25*25

double X[MAXN];
double Y[MAXN];
double Z[MAXN];

int FSZ[25];
int F[25][25];

/* Compute the hypervolume of the 3D simplex.  This is just the determinant of
 * the edge vectors divided by 3!. */
double simplex3(int a, int b, int c, int d) {
  double A[3][3];
  A[0][0] = X[b] - X[a]; A[0][1] = Y[b] - Y[a]; A[0][2] = Z[b] - Z[a];
  A[1][0] = X[c] - X[a]; A[1][1] = Y[c] - Y[a]; A[1][2] = Z[c] - Z[a];
  A[2][0] = X[d] - X[a]; A[2][1] = Y[d] - Y[a]; A[2][2] = Z[d] - Z[a];

  return fabs(A[0][0] * A[1][1] * A[2][2] +
              A[0][1] * A[1][2] * A[2][0] +
              A[0][2] * A[1][0] * A[2][1] -
              A[0][0] * A[1][2] * A[2][1] -
              A[0][1] * A[1][0] * A[2][2] -
              A[0][2] * A[1][1] * A[2][0]);
}

int main() {
  for(int t = 1; ; t++) {
    int N; cin >> N;
    if(!N) break;

    double area = 0;
    for(int k = 0; k < N; k++) {
      int p = 0;
      int M; cin >> M;
      for(int i = 0; i < M; i++) {
        cin >> FSZ[i];
        for(int j = 0; j < FSZ[i]; j++) {
          cin >> X[p] >> Y[p] >> Z[p];
          F[i][j] = p++;
        }
      }

      for(int i = 1; i < M; i++) {
        for(int j = 1; j + 1 < FSZ[i]; j++) {
          area += simplex3(F[0][0], F[i][0], F[i][j], F[i][j + 1]);
        }
      }
    }

    printf("%.2f\n", area / 6);
  }
}