import java.util.Scanner;
class Chap5a
{
  public static void main(String[] args)
  {
    Scanner sc=new Scanner(System.in);
//**********************************************************************
//                                                                     *
//     Get the number of histories desired                             *
//                                                                     *
//**********************************************************************
    while(true)
    {
      int n=0;
      System.out.println("\n N?");
      int ntry=sc.nextInt();
      if(ntry < 0)System.exit(0);
      if(ntry >0)n=ntry;
//**********************************************************************
//                                                                     *
//     Initialize the two bins we will be collecting information in.   *
//                                                                     *
//**********************************************************************
      double total_score=0.;
      double total_squared=0.;
//**********************************************************************
//                                                                     *
//     For each history:                                               *
//                                                                     *
//**********************************************************************
      for(int ihistory=0;ihistory<n;ihistory++)
      {
//**********************************************************************
//                                                                     *
//       Call getScore to get the score for this history               *
//                                                                     *
//**********************************************************************
        double score=getScore();
//**********************************************************************
//                                                                     *
//       Contribute to the average and average_squared bins            *
//                                                                     *
//**********************************************************************
        total_score+=score;
        total_squared+=score*score;
      }
//**********************************************************************
//                                                                     *
//     After all histories have been run:                              *
//                                                                     *
//       Find the estimate of the average                              *
//                                                                     *
//**********************************************************************
      double xhat=total_score/n;
      double x2hat=total_squared/n;
//**********************************************************************
//                                                                     *
//       Find the sample variance and sample standard deviation        *
//                                                                     *
//**********************************************************************
      double sample_variance=(double)n/(double)(n-1)*(x2hat-xhat*xhat);
      double sample_sd=Math.sqrt(sample_variance);
//**********************************************************************
//                                                                     *
//       Find the mean variance and mean standard deviation            *
//                                                                     *
//**********************************************************************
      double mean_variance=sample_variance/(double)(n-1);
      double mean_sd=Math.sqrt(mean_variance);
//**********************************************************************
//                                                                     *
//       Print out the results for this run                            *
//                                                                     *
//**********************************************************************
      System.out.printf(" For = %1$9d ==> %2$10.5e +/- %3$10.5e  (%4$6.3f percent)\n",
      n,xhat,mean_sd,mean_sd/xhat*100.);
      System.out.printf("       Standard deviation of process ==> %1$10.5e",sample_sd);
    }
  }
//**********************************************************************
//**********************************************************************
  static double  getScore()
  {
    double x=2.*Math.random();
    double y=4.*Math.random();
    double ret=0.;
    if(y<x*x)ret=8;
    return ret;
  }
}