// Reverse Polish calculator
// A Program demonstrating the use of the stack

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

class polish {

  public static void main (String[] args) throws IOException {

    BufferedReader stdin;
    stdin = new BufferedReader (new InputStreamReader (System.in));

    System.out.print("Type an expression in postfix form: ");

    StringTokenizer expr = new StringTokenizer(stdin.readLine(), " +-*/", true);

    String token;
    Stack s = new Stack();
    float a, b;

    mystack z = new mystack();

    while (expr.hasMoreTokens()) {
      token = expr.nextToken();
      switch (token.charAt(0)) {
         case ' ':                                    // skip the space;
            break;
         case '+':
            a = ((Float)s.pop()).floatValue();
            b = ((Float)s.pop()).floatValue();
            s.push(new Float(a + b)); 
            break;
         case '-':
            b = ((Float)s.pop()).floatValue();        // note the order: pop b, pop a.
            a = ((Float)s.pop()).floatValue();
            s.push(new Float(a - b)); 
            break;
         case '*':
            a = ((Float)s.pop()).floatValue();
            b = ((Float)s.pop()).floatValue();
            s.push(new Float(a * b)); 
            break;
         case '/':
            b = ((Float)s.pop()).floatValue();        // note the order: pop b, pop a.
            a = ((Float)s.pop()).floatValue();
            s.push(new Float(a / b)); 
            break;
         default : 
            s.push(Float.valueOf(token));
            break;
      }

      if (token.charAt(0) != ' ') {                   // Print the current toke
         System.out.print("Token: " + token + "\t");  // and the stack contents
         z.print_stack(s);
      }

    }

    System.out.println("------------------------------\nThe value is: " + s.pop());
  }

}