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


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 ();
    // Returns the element on the top od the stack.

    // Transformation methods:

    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 of 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<Integer> stack = new ArrayStack(n);
        StringBuilder bs = new StringBuilder();

        for (int i = 0 ; i < izraz.length ; i++) {

            //System.err.println(izraz[i]);

            if (izraz[i] == '+') {

                stack.push(stack.pop() + stack.pop());

            } else if (izraz[i] == '-') {

                int x = stack.pop();
                int y = stack.pop();

                stack.push(y - x);

            } else if (izraz[i] == '*') {

                stack.push(stack.pop() * stack.pop());

            } else if (izraz[i] == '/') {

                int x = stack.pop();
                int y = stack.pop();

                if (y == 0) stack.push(0);

                else stack.push(y / x);

            } else if (izraz[i] == ' ') {

                if (bs.length() > 0) {

            	String value = bs.toString();

                stack.push(Integer.parseInt(value));

                bs.setLength(0);

                }

                continue;

            } else {

                bs.append(izraz[i]);

            }

        }

        return stack.peek();

    }

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

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

        String expression = br.readLine();
        char exp[] = expression.toCharArray();
        // char exp[] = new char[]{'1', '2', '+'};

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

        br.close();

    }

}