import java.util.Scanner;
// Dr Nim video https://www.youtube.com/watch?v=9KABcmczPdg
public class DrNim
{
  private static Scanner kb;

  private int marblesLeft;

  public DrNim(int n)
  {
    marblesLeft = n;
  }

  /*
   * Returns a random number of marbles (1-3) to take
   * Precondition: nmarbles > 0
   */
  public int computerMove()
  {
       ///Your code here ____________________________
  }

  public int humanMove(int nMarbles)
  {
    System.out.print("How many marbles do you take? ");
    int n = kb.nextInt();
    while (n < 1 || n >3){
        System.out.println("You are allowed to only take 1, 2, or 3 marbles");
        n = kb.nextInt();
    }
    return n;
  }

  public void play()
  {
    while (marblesLeft > 0)
    {
       System.out.println();
        for(int i=0; i < marblesLeft; i++)
            System.out.print("O ");
        System.out.println("\n"+marblesLeft + " marble(s) left in the pile");

      int n = -1;
      while (n < 0)
        n = humanMove(marblesLeft);
      marblesLeft -= n;
      System.out.println("You took " + n + " marble(s)");
      if (marblesLeft == 0)
      {
        System.out.println("You won!");
      }
      else
      {
        n = computerMove();
        marblesLeft -= n;
        System.out.println("I take " + n + " marble(s)");
        if (marblesLeft == 0)
          System.out.println("I won!");
      }
    }
  }

  public static void main(String[] args)
  {
    kb = new Scanner(System.in);
    DrNim game = new DrNim(12);
    game.play();
    kb.close();
  }
}