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

public class Zagradi<E>{
	public static class ArrayStack<E>  {

	    // Stekot e pretstaven na sledniot nacin:
		//depth e dlabochinata na stekot, a
	    // elems[0...depth-1] se negovite elementi.
	    private E[] elems;
	    private int depth;

	    @SuppressWarnings("unchecked")
	    public ArrayStack (int maxDepth) {
	        // Konstrukcija na nov, prazen stek.
	        elems = (E[]) new Object[maxDepth];
	        depth = 0;
	    }


	    public boolean isEmpty () {
	        // Vrakja true ako i samo ako stekot e prazen.
	        return (depth == 0);
	    }


	    public E peek () {
	        // Go vrakja elementot na vrvot od stekot.
	        if (depth == 0)
	            throw new NoSuchElementException();
	        return elems[depth-1];
	    }


	    public void clear () {
	        // Go prazni stekot.
	        for (int i = 0; i < depth; i++)  elems[i] = null;
	        depth = 0;
	    }


	    public void push (E x) {
	        // Go dodava x na vrvot na stekot.
	        elems[depth++] = x;
	    }


	    public E pop () {
	        // Go otstranuva i vrakja elementot shto e na vrvot na stekot.
	        if (depth == 0)
	            throw new NoSuchElementException();
	        E topmost = elems[--depth];
	        elems[depth] = null;
	        return topmost;
	    }
	}
	public static boolean isDigit(char x) {
		int a = (int) x;
		return( a == 1 || a == 2 || a == 3 || a == 4 || a == 5 || a == 6 || a == 7 || a == 8 || a == 9);
	}

	public static int evaluacija (char exp[]) {
		ArrayStack<Integer> stekce = new ArrayStack<Integer>(100);
		for(int i=0;i<exp.length;i++) {
			if (isDigit(exp[i])) {
				int a = (int) exp[i];
				stekce.push(a);
			}
			else if (exp[i] == '+' || exp[i] == '*') {
				int x = stekce.pop();
				int y = stekce.pop();
				if (exp[i] == '+') {
					int z = x + y;
					stekce.push(z);
				}
				if (exp[i] == '*') {
					int z = x * y;
					stekce.push(z);
				}
			}
		}
		return stekce.pop();
	}


   public static void main (String[] args) throws IOException {
	   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

       String expression = br.readLine();
       char exp[] = expression.toCharArray();
       int x = evaluacija(exp);
       System.out.print(x);

       br.close();
   }
  }