import java.util.*;
import java.util.Scanner;

public class postfix {
    public static void main(String[] args) {
      myStack s = new myStack();

      Scanner input = new Scanner(System.in);
      System.out.println("Please input string");
      String stringInput = input.nextLine();
      String[] numbers = stringInput.split(" ");
      for (int i= 0; i< numbers.length; i++){
        try {
          int tempholder = Integer.parseInt(numbers[i]);
          s.push(numbers[i]);
        }
        catch(NumberFormatException e){
          String op = numbers[i];
          try{
            int num2 = Integer.parseInt(s.pop());
            int num1 = Integer.parseInt(s.pop());
            if (op.equals("+")){
              s.push(Integer.toString((num1 + num2)));
            }
            else if (op.equals("-")){
              s.push(Integer.toString((num1 + num2)));
            }
            else if (op.equals("*")){
              s.push(Integer.toString((num1 * num2)));
            }
            else if (op.equals("/")){
              s.push(Integer.toString((num1 / num2)));
            }
          }
          catch(Exception f){
            System.out.println("Pop Failed");
          }
          try{
          s.pop();
          }
          catch (Exception g){
          }
        }

      }