/*
 * Copyright (c) 2008, Manuel Mausz <manuel at mausz.at>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the copyright holders nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

import java.util.Scanner;

/**
 * Implements a simple RPN (UPN) Calculator
 * - Parses the given input syntax
 * - passes them to the RPN Calculator
 * - and prints the specified (tho completely non-informative) error messages
 *
 * @version 1.0
 * @author  Manuel Mausz (manuel at mausz.at)
 * @author  http://manuel.mausz.at/
 */
class UpnApplication
{
  private static UpnCalculator calc = new UpnCalculator();

  /**
   * read operands and operator from first line of src
   * parses RPN syntax; only allows integers as operands
   * prints "?" to stdout if calculations fails
   *
   * @param src input stream
   * @return boolean true on success, false otherwise
   */
  private static boolean parse(java.io.InputStream src)
  {
    Scanner scan;

    /* get first line only */
    scan = new Scanner(src);
    if (!scan.hasNextLine())
    {
      scan.close();
      return false;
    }
    String line1 = scan.nextLine();
    scan.close();

    /* parse first line */
    scan = new Scanner(line1);
    boolean err = false;
    while(!err && scan.hasNext())
    {
      /* pass operand or operator to UpnCalculator */
      if (scan.hasNextInt())
        calc.addOperand(scan.nextInt());
      else if (scan.hasNext())
      {
        String op = scan.next();
        if (!calc.supportsOperator(op))
          err = true;
        else if (!calc.addOperator(op))
          System.out.println("?");
      }
      else
        err = true;
    }
    scan.close();

    return !err;
  }

  /**
   * main method
   *
   * @param args not used
   */
  public static void main(String args[])
  {
    /* try-catch for the sake of safety */
    try
    {
      /* dump RPN stack of everything was ok */
      if (parse(System.in))
        System.out.print(calc);
      else
        System.out.println("FALSCHE EINGABE");
    }
    catch(Throwable e)
    {
      System.out.println("FALSCHE EINGABE");
    }
  }
}