import java.io.*;

class Average9
{
/*
 A program that calculates the average of a series of integers read
 from a file. A sentinel value is used to indicate the
 end of the series. 
 The program prompts for the name of the file the numbers are to be read
 from.
*/
  
 static final int SENTINEL = -999;

 public static void main(String[] args) throws IOException
 {
  BufferedReader in = Text.open(System.in);
  BufferedReader fileReader;
  String filename;
  int sum=0,count=0,n;
  System.out.print("Enter file name to read from: ");
  filename=Text.readString(in);
  try
     {
      fileReader=Text.open(filename);
      n=Text.readInt(fileReader);
      while(n!=SENTINEL)
         {
          sum+=n;
          count++;
          n=Text.readInt(fileReader);
         }
     }
  catch(EOFException e)
     {
      System.out.println("No sentinel "+SENTINEL+" found in file");
     }
  catch(FileNotFoundException e)
     {
      System.out.println("File "+filename+" not found");
     }
  System.out.println("Average is: "+Text.writeDouble((double)sum/count,5,3));
 }
}