import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;

interface Stack<E> {

    // The elements of the Stack are any kind of objects

    // Access methods:

    public boolean isEmpty ();
        // Returns true only if the stack is empty.

 public E peek ();

    public void clear ();
        // Clears the stack.

    public void push (E x);
        // Adds x on the top of the stack.

    public E pop ();
        // Removes and returns the element on the top.


}

class ArrayStack<E> implements Stack<E> {
    private E[] elems;
    private int depth;

    @SuppressWarnings("unchecked")
    public ArrayStack (int maxDepth) {
        // Creating new empty stack
        elems = (E[]) new Object[maxDepth];
        depth = 0;
    }


    public boolean isEmpty () {
         // Returns true only if the stack is empty.

        return (depth == 0);
    }

  public E peek () {
        // Returns the element on the top od the stack.
        if (depth == 0)
            throw new NoSuchElementException();
        return elems[depth-1];
    }


    public void clear () {
        // Clears the stack.
        for (int i = 0; i < depth; i++)  elems[i] = null;
        depth = 0;
    }


    public void push (E x) {
        // Adds x on the top of the stack.
        elems[depth++] = x;
    }


    public E pop ()
    {
        // Removes and returns the element on the top.
        if (depth == 0)
            throw new NoSuchElementException();
        E topmost = elems[--depth];
        elems[depth] = null;
        return topmost;
    }


}


public class PostFixEvaluation {


    static int evaluatePostfix(char [] izraz, int n)
    {
        ArrayStack<String> e = new ArrayStack<String>(n);
        char ch=0,res=0;
        int op1,op2,result=0;
        int z,i=0;
      for(i=0; i<n; i++);
    {

        if(Character.isDigit(izraz[i]))
       {
         final StringBuilder number= new StringBuilder();

         while (izraz[i] != ' ') {
           number.append(izraz[i]);
           i++;
         }

         e.push(number.toString());

       }

            if(izraz[i]=='+' || izraz[i]=='-' || izraz[i]=='/' || izraz[i]=='*')
           {
                ch=izraz[i];
                op1 =Integer.parseInt(e.pop());
                op2 =Integer.parseInt(e.pop());


               if(ch=='+')
               {
               result=op1+op2;

               }
                if(ch=='-')
               {

               result=op2-op1;
               }
                if(ch=='/')
               {
                    if(op1==0 || op2==0)result=0;
                    else
               result=op1/op2;
               }
                if(ch=='*')
               {
               result=op1*op2;
               }

                 e.push(Integer.toString(result));

           }


           }


        return result;
}

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

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

        String expression = br.readLine();
        char exp[] = expression.toCharArray();

        int rez = evaluatePostfix(exp, exp.length);
        System.out.println(rez);

        br.close();

    }

}