/* package whatever; // don't place package name! */

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

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static boolean isNumber(String s){
		try{
			Integer.parseInt(s);
			return true;
		}catch(Exception e){
			return false;
		}
	}
	
	public static String calc(String s1, String s2, String method){
		String ret = "";
        switch(method){
            case "+":
                ret = String.valueOf(Integer.parseInt(s1) + Integer.parseInt(s2));
                break;
            case "-":
                ret = String.valueOf(Integer.parseInt(s1) - Integer.parseInt(s2));
                break;
            case "*":
                ret = String.valueOf(Integer.parseInt(s1) * Integer.parseInt(s2));
                break;
            case "/":
                ret = String.valueOf(Integer.parseInt(s1) / Integer.parseInt(s2));
                break;
        }
        return ret;
	}
	
	public static void main (String[] args) throws java.lang.Exception
	{
		Stack<String> s = new Stack();
		
		String test = "3 5 + 1 * 2 3 - -";
		
		String[] sa = test.split(" ");
		
		for(int i = 0; i < sa.length; i++){
			if(isNumber(sa[i])){
				s.push(sa[i]);
			}else{
				String s2 = s.pop();
				String s1 = s.pop();
				String newVal = calc(s1, s2, sa[i]);
				s.push(newVal);
			}
		}
		
		System.out.println(s.pop());
	}
}