import java.io.*;
import java.util.*;

/*
6 4 3 + + 3 8 2 * + * 2 + 3 +
9 6 2 * 7 * 12 5 9 6 - * + * +
1 2 - 4 5 $ 3 * 6 * 7 2 2 $ $ / -
8 2 5 + * 2 / 4 $ 6 3 12 * / -
*/

public class Lab7 
{
    private String filename;
    
    public static void main(String args[])
    {
	
	Lab7 l = new Lab7();
	l.requestFile();
	
	try
	{
	    BufferedReader br = new BufferedReader(new FileReader(l.getFilename()));
	    String line = "";
	    while(  ((line = br.readLine()) != null)   )
	    {
		boolean goodline = true;
		StackArrayBased s = new StackArrayBased();
		String tokLine = "";
		StringTokenizer tok = new StringTokenizer(line);
		while(tok.hasMoreTokens())
		{
		    tokLine = tok.nextToken().trim();
		    //System.out.println("tok> " + tokLine);
		    if( (tokLine.equalsIgnoreCase("+")) || 
		        (tokLine.equalsIgnoreCase("-")) || 
		        (tokLine.equalsIgnoreCase("*")) || 
		        (tokLine.equalsIgnoreCase("/")) || 
		        (tokLine.equalsIgnoreCase("$")) )
		    {
			//System.out.println("Symbol> " + tokLine);
			//
			if(!s.isEmpty())
			{	
			    //6 4 3 + + 3 8 2 * + * 2 + 3 +
			    Integer i = (Integer)s.pop();
			    int temp1 = i.intValue();
			    //System.out.println("POP> " + i);
			    
			    if(!s.isEmpty())
			    {
				i = (Integer)s.pop();
			    }
			    else
			    {
				System.out.println("Stack is empty,,, program terminated");
				System.exit(-1);
			    }
			    int temp2 = i.intValue();
			    //System.out.println("POP> " + i);
			    int temp3 = 0;
			    
			    if(tokLine.equalsIgnoreCase("+"))
			    {
				temp3 = temp2 + temp1;
			    }
			    else if(tokLine.equalsIgnoreCase("-"))
			    {
				temp3 = temp2 - temp1;
			    }
			    else if(tokLine.equalsIgnoreCase("*"))
			    {
				temp3 = temp2 * temp1;
			    }
			    else if(tokLine.equalsIgnoreCase("/"))
			    {
				temp3 = temp2 / temp1;
			    }
			    else if(tokLine.equalsIgnoreCase("$"))
			    {
				temp3 = (int)Math.pow((double)temp2,(double)temp1);
			    }
			    else
			    {
				System.out.println("Incorrect Symbol");
			    }
			    s.push(new Integer(temp3));			    
			}
			//
			
		    }
		    else if(tokLine.equalsIgnoreCase(""))
		    {
			System.out.println("End of line reached");
			goodline = false;
		    }
		    else
		    {
			if(!s.isFull())
			{
			    int t = Integer.parseInt(tokLine);
			    //System.out.println("PUSH> " + t);
			    s.push(new Integer(t));
			}
			
		    }
		    
		    
		}
		
		if(goodline)
		{
		    ///this is the last one
		    Integer j = (Integer)s.pop();
		    int temp4 = j.intValue();
		    System.out.println(line + "\tvalue of postfix expression is " + temp4);
		    System.out.println();
		    //System.out.println("Value Is> " + temp4);
		}
		else
		{
		    System.out.println("a blank line was encountered");
		}
	    }
	}
	catch(Exception e)
	{
	    System.out.println("Error> " + e);
	}
    }
    
    public Lab7()
    {
	filename = "";
    }
    
    public void setFilename(String f)
    {
	filename = f;
    }
    
    public String getFilename()
    {
	return filename;
    }
    
    public void requestFile()
    {
	String file = "";
	try
	{
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	    System.out.print("Enter Filename> ");
	    //file = br.readLine();
	    file = "C:\\Johnny\\School\\cs2003\\lab7\\postfix.dat";
	    setFilename(file);
	}
	catch(Exception e)
	{
	    System.out.println("Error> " + e);
	}
    }    
}