import java.util.Scanner;
class MCBase2
{
//**********************************************************************
//                                                                     *
// Set up Halton sequences by putting in the base                      *
//                                                                     *
//**********************************************************************
  static Halton halx=new Halton(2);
  static Halton haly=new Halton(3);
  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 class Halton
  {
    public int base;
    int count=0;
    double previous=0.;
    Halton(int base0)
    {
      base=base0;
    }

    double next()
    {
      count++;
      int j=count;
      double frac=1./base;
      double ret=0.;
      while(j != 0)
      {
        int idigit=j - (j/base)*base;
        ret+=idigit*frac;
        j=(j-idigit)/base;
        frac/=base;
      }
      return ret;
    }
  }

  static double  getScore()
  {
//**********************************************************************
//                                                                     *
//    double x=Math.random();                                          *
//                                                                     *
//**********************************************************************
    double x=halx.next();
    double y=haly.next();
    return x+y;
  }
}