/**
   Boston University, Department of Computer Science
   CS 112 Lab 01: Recursion 
   Teaching Fellow: Diane H. Theriault, deht@cs.bu.edu
 */

import java.io.*;

public class PowerRunner {
  
  public static void main(String[] args)
  {
    System.out.println("Hello CS112! This program computes x^n.");
    
    System.out.println("Please enter x:");
    int x = getNumberFromKeyboard();
    System.out.println("Please enter n:");
    int n = getNumberFromKeyboard();

    if(x < 0 || n < 0)
    {
      System.out.println("This program only works with non-negative integers");
      return; //exit
    }
    else
    {
      System.out.println("Computing " + x + "^" + n);
      PowerComputer computer = new PowerComputer();
      double myResult = computer.exponentiate(x, n);
      double javaResult = Math.pow(x,n);
      System.out.println("My result: " + myResult + ". Java's result: " + javaResult);
      
      int iterations = computer.getNumIterations();
      System.out.println("Iterations needed: "+ iterations);
    }
  }
  
  public static int getNumberFromKeyboard() 
  {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    String s = null;
    int answer = -1;

    try{
      s = in.readLine();
      if(s == null || s.length() == 0)
      {
        System.out.println("String from keyboard is empty");
        return -1;
      }
      answer = Integer.parseInt(s);
    }
    catch(java.io.IOException exception)
    {
      System.out.println("Problem reading the line");
    }
    catch(java.lang.NumberFormatException exception)
    {
      System.out.println("Unable to convert this string to an integer: " + s);
    }
 
    return answer;
  }
}