/*
 *    Std.java 
 */


public class Std
{
   public static void main (String args[]) 
   {
      // declaring a constant variable
      final int NUM = 7;

      int number = 0;
      int total = 0;
      int counter = 0;
      double average;
      int values[] = new int[7];
       int times[] = new int[7];
      boolean done = false;
      double term,sum=0;
      double std;


      while (!done)
      { 
      /* uses method from Console class to read formatted input -
                prints the argument as a prompt, then reads an int
                terminated by a newline */
	values[counter] = Console.readInt("Value: ");
        times[counter] = Console.readInt("   times: ");
	total += values[counter] * times[counter];
        number += times[counter];
	if (values[counter]==0) done = true;
        counter ++;
      }

      // cast to get floating point arithmetic
      average = (double)total / number;
      for (int i=0; i < counter; i++)
      {
       term = (average - values[i]);
       sum = sum + term * term * times[i];
      }
       std = Math.sqrt(sum / number);
      System.out.println ("The mean of these numbers is " + average );
      System.out.println ("The std of these numbers is " + std);
   }
}